diff --git a/journal/src/journal.rs b/journal/src/journal.rs
index f93575c..d91349e 100644
--- a/journal/src/journal.rs
+++ b/journal/src/journal.rs
@@ -5,24 +5,29 @@ use crate::types::{
 pub type JournalType = Box<dyn Journal>;
 
 pub trait Journal {
-	fn get_custom_unit(&self, id: i32) -> Option<CustomUnit>;
+	fn save(&self) -> Result<(), Box<dyn std::error::Error>>;
+
 	fn get_session(&self, id: i32) -> Option<Session>;
 	fn get_session_ingestions(&self, id: i32) -> Option<Vec<Ingestion>>;
-
 	fn get_substance(&self, name: &str) -> Option<Substance>;
-	fn get_sustenance(&self, sustenance_id: &str) -> Option<Sustenance>;
-	fn get_sustenance_ingestions(&self, sustenance_id: &str) -> Option<Vec<IngestionKind>>;
+	fn get_sustenance(&self, id: &str) -> Option<Sustenance>;
+	fn get_sustenance_ingestions(&self, id: &str) -> Option<Vec<IngestionKind>>;
+	fn get_custom_unit(&self, id: i32) -> Option<CustomUnit>;
+
+	fn create_session(&mut self, title: &str) -> Session;
+	fn create_substance(&mut self, substance: Substance) -> Substance;
+	fn create_sustenance(&mut self, sustenance: Sustenance) -> Sustenance;
+	fn create_custom_unit(&mut self, unit: CustomUnit) -> CustomUnit;
+
+	fn update_session(&mut self, id: i32, session: Session, create: bool);
+	fn update_substance(&mut self, name: &str, substance: Substance, create: bool);
+	fn update_sustenance(&mut self, id: &str, sustenance: Sustenance, create: bool);
+	fn update_custom_unit(&mut self, id: i32, unit: CustomUnit, create: bool);
 
-	fn set_custom_unit(&mut self, unit: CustomUnit);
-	fn set_session(&mut self, session: Session);
 	fn set_session_ingestions(&mut self, session_id: i32, ingestions: Vec<Ingestion>);
-	fn set_substance(&mut self, substance: Substance);
-	fn set_sustenance(&mut self, sustenance: Sustenance);
 
 	fn first_session_by_title(&self, title: &str) -> Option<Session>;
 	fn resolve_substance_unit(&self, ingestion: &SubstanceIngestion) -> Option<Unit>;
-
-	fn save(&self) -> Result<(), Box<dyn std::error::Error>>;
 }
 
 mod json_journal;
diff --git a/journal/src/journal/json_journal.rs b/journal/src/journal/json_journal.rs
index 0479565..d0e796e 100644
--- a/journal/src/journal/json_journal.rs
+++ b/journal/src/journal/json_journal.rs
@@ -1,5 +1,8 @@
 use std::{collections::HashMap, fs::File};
 
+use chrono::Utc;
+use rand::Rng;
+
 use crate::types::{
 	CustomUnit, Ingestion, IngestionKind, Session, Substance, SubstanceIngestion, Sustenance, Unit,
 };
@@ -59,8 +62,8 @@ impl JSONJournal {
 }
 
 impl Journal for JSONJournal {
-	fn get_custom_unit(&self, id: i32) -> Option<CustomUnit> {
-		self.data.custom_units.get(&id).cloned()
+	fn save(&self) -> Result<(), Box<dyn std::error::Error>> {
+		self.save()
 	}
 
 	fn get_session(&self, id: i32) -> Option<Session> {
@@ -75,58 +78,12 @@ impl Journal for JSONJournal {
 		self.data.substances.get(name).cloned()
 	}
 
-	fn resolve_substance_unit(&self, ingestion: &SubstanceIngestion) -> Option<Unit> {
-		match ingestion.custom_unit_id {
-			None => match self.get_substance(&ingestion.substance_name) {
-				Some(substance) => Some(Unit::Simple(substance.unit)),
-				None => None,
-			},
-			Some(custom_unit_id) => self.get_custom_unit(custom_unit_id).map(Unit::Custom),
-		}
-	}
-
-	fn first_session_by_title(&self, title: &str) -> Option<Session> {
-		self.data
-			.sessions
-			.values()
-			.find(|&session| session.title == title)
-			.cloned()
-	}
-
-	fn set_custom_unit(&mut self, unit: CustomUnit) {
-		self.data.custom_units.insert(unit.id, unit);
-	}
-
-	fn set_session(&mut self, session: Session) {
-		self.data.sessions.insert(session.id, session);
-	}
-
-	fn set_session_ingestions(&mut self, session_id: i32, ingestions: Vec<Ingestion>) {
-		self.data.ingestions.insert(session_id, ingestions);
-	}
-
-	fn set_substance(&mut self, substance: Substance) {
-		self.data
-			.substances
-			.insert(substance.name.clone(), substance);
-	}
-
-	fn save(&self) -> Result<(), Box<dyn std::error::Error>> {
-		self.save()
-	}
-
 	fn get_sustenance(&self, sustenance_id: &str) -> Option<Sustenance> {
 		self.data.sustenances.get(sustenance_id).cloned()
 	}
 
-	fn set_sustenance(&mut self, sustenance: Sustenance) {
-		self.data
-			.sustenances
-			.insert(sustenance.id.clone(), sustenance);
-	}
-
 	fn get_sustenance_ingestions(&self, sustenance_id: &str) -> Option<Vec<IngestionKind>> {
-		let sustenance = self.get_sustenance(sustenance_id).unwrap();
+		let sustenance = self.get_sustenance(sustenance_id)?;
 
 		let mut ingestions: Vec<IngestionKind> = Vec::new();
 		for include in sustenance.includes.into_iter() {
@@ -152,4 +109,107 @@ impl Journal for JSONJournal {
 
 		Some(ingestions)
 	}
+
+	fn get_custom_unit(&self, id: i32) -> Option<CustomUnit> {
+		self.data.custom_units.get(&id).cloned()
+	}
+
+	fn create_session(&mut self, title: &str) -> Session {
+		let id = rand::thread_rng().gen::<i32>();
+
+		let session = Session {
+			id,
+			title: title.to_string(),
+			creation_time: Utc::now(),
+			..Session::default()
+		};
+
+		self.data.sessions.insert(id, session.clone());
+
+		session
+	}
+
+	fn create_substance(&mut self, substance: Substance) -> Substance {
+		self.data
+			.substances
+			.insert(substance.name.clone(), substance.clone());
+
+		substance
+	}
+
+	fn create_sustenance(&mut self, sustenance: Sustenance) -> Sustenance {
+		self.data
+			.sustenances
+			.insert(sustenance.id.clone(), sustenance.clone());
+
+		sustenance
+	}
+
+	fn create_custom_unit(&mut self, unit: CustomUnit) -> CustomUnit {
+		let id = rand::thread_rng().gen::<i32>();
+
+		let unit = CustomUnit { id, ..unit };
+
+		self.data.custom_units.insert(id, unit.clone());
+
+		unit
+	}
+
+	fn update_session(&mut self, id: i32, session: Session, create: bool) {
+		assert!(self.data.sessions.contains_key(&id) || create);
+
+		self.data.sessions.insert(id, Session { id, ..session });
+	}
+
+	fn update_substance(&mut self, name: &str, substance: Substance, create: bool) {
+		assert!(self.data.substances.contains_key(name) || create);
+
+		self.data.substances.insert(
+			name.to_string(),
+			Substance {
+				name: name.to_string(),
+				..substance
+			},
+		);
+	}
+
+	fn update_sustenance(&mut self, id: &str, sustenance: Sustenance, create: bool) {
+		assert!(self.data.sustenances.contains_key(id) || create);
+
+		self.data.sustenances.insert(
+			id.to_string(),
+			Sustenance {
+				id: id.to_string(),
+				..sustenance
+			},
+		);
+	}
+
+	fn update_custom_unit(&mut self, id: i32, unit: CustomUnit, create: bool) {
+		assert!(self.data.custom_units.contains_key(&id) || create);
+
+		self.data.custom_units.insert(id, CustomUnit { id, ..unit });
+	}
+
+	fn set_session_ingestions(&mut self, session_id: i32, ingestions: Vec<Ingestion>) {
+		self.data.ingestions.insert(session_id, ingestions);
+	}
+
+	fn first_session_by_title(&self, title: &str) -> Option<Session> {
+		self.data
+			.sessions
+			.values()
+			.find(|&session| session.title == title)
+			.cloned()
+	}
+
+	fn resolve_substance_unit(&self, ingestion: &SubstanceIngestion) -> Option<Unit> {
+		match ingestion.custom_unit_id {
+			None => match self.get_substance(&ingestion.substance_name) {
+				Some(substance) => Some(Unit::Simple(substance.unit)),
+				None => None,
+			},
+			Some(custom_unit_id) => self.get_custom_unit(custom_unit_id).map(Unit::Custom),
+		}
+	}
 }
diff --git a/journal_cli/src/commands/journal/import_psychonaut.rs b/journal_cli/src/commands/journal/import_psychonaut.rs
index 44e8687..ca7fa5e 100644
--- a/journal_cli/src/commands/journal/import_psychonaut.rs
+++ b/journal_cli/src/commands/journal/import_psychonaut.rs
@@ -1,7 +1,7 @@
 use std::{collections::HashMap, fs::File, path::Path};
 
 use journal::{
-	journal::{JSONJournal, Journal},
+	journal::{JSONJournal, Journal, JournalType},
 	types::{CustomUnit, Ingestion, Session, Substance},
 };
 use rand::Rng;
@@ -22,8 +22,13 @@ pub struct JournalImportPsychonautArgs {
 	#[arg(long)]
 	pub force_create: bool,
 
-	#[arg(long, value_hint = clap::ValueHint::FilePath)]
-	pub mappings_file: Option<String>,
+	#[arg(long)]
+	pub custom_unit_id: Option<i32>,
+	#[arg(long)]
+	pub custom_unit_name: Option<String>,
+
+	#[arg(long)]
+	pub custom_substance: Option<String>,
 
 	#[arg(long)]
 	pub infer_missing_substances: bool,
@@ -52,49 +57,126 @@ pub fn journal_import_psychonaut(
 	let export_file = File::open(args.export_file.clone())?;
 	let export_data: psychonaut_journal_types::ExportData = serde_json::from_reader(export_file)?;
 
-	let mappings: Mappings = match args.mappings_file.clone() {
-		Some(filename) => {
-			let mappings_file = File::open(filename)?;
-			let mappings_data: Mappings = serde_json::from_reader(mappings_file)?;
-			mappings_data
-		}
-		None => Mappings::default(),
-	};
-
 	let mut rng = rand::thread_rng();
 
-	for custom_unit in export_data.custom_units.into_iter() {
-		journal.set_custom_unit(CustomUnit::from(custom_unit));
+	fn create_or_update_custom_unit(journal: &mut JournalType, unit: CustomUnit) {
+		match journal.get_custom_unit(unit.id) {
+			Some(custom_unit) => {
+				println!(
+					"Updating Custom Unit ID: {} Name: {}",
+					unit.id, custom_unit.name
+				);
+				journal.update_custom_unit(unit.id, unit, false);
+			}
+			None => {
+				println!("Creating Custom Unit ID: {} Name: {}", unit.id, unit.name);
+				journal.update_custom_unit(unit.id, unit, true);
+			}
+		}
 	}
 
-	for custom_substance in export_data.custom_substances.into_iter() {
+	if let Some(id) = &args.custom_unit_id {
+		let unit = export_data
+			.custom_units
+			.into_iter()
+			.find(|unit| unit.id == *id);
+
+		match unit {
+			Some(unit) => {
+				create_or_update_custom_unit(&mut journal, CustomUnit::from(unit));
+			}
+			None => {
+				panic!("Could not find custom unit with ID: {id}")
+			}
+		}
+
+		return Ok(());
+	} else if let Some(name) = &args.custom_unit_name {
+		let unit = export_data
+			.custom_units
+			.into_iter()
+			.find(|unit| unit.name == *name);
+
+		match unit {
+			Some(unit) => {
+				create_or_update_custom_unit(&mut journal, CustomUnit::from(unit));
+			}
+			None => {
+				panic!("Could not find custom unit with name: {name}")
+			}
+		}
+
+		return Ok(());
+	} else if args.custom_substance.is_none() {
+		for custom_unit in export_data.custom_units.into_iter() {
+			create_or_update_custom_unit(&mut journal, CustomUnit::from(custom_unit));
+		}
+	}
+
+	fn create_or_check_custom_substance(
+		journal: &mut JournalType,
+		args: &JournalImportPsychonautArgs,
+		custom_substance: Substance,
+	) {
 		match journal.get_substance(&custom_substance.name) {
 			Some(substance) => {
-				if substance.unit != custom_substance.units {
+				println!("Checking substance units {}", custom_substance.name);
+
+				if substance.unit != custom_substance.unit {
 					panic!(
-						"mismatch on units for {}: {} != {} ",
-						custom_substance.name, substance.unit, custom_substance.units
+						"mismatch on unit for {}: {} != {} ",
+						custom_substance.name, substance.unit, custom_substance.unit
 					)
 				}
 			}
 			None => {
 				if args.infer_missing_substances {
-					journal.set_substance(Substance {
-						name: custom_substance.name.clone(),
-						description: custom_substance.description.clone(),
-						unit: custom_substance.units,
-					});
+					println!("Creating substance {}", custom_substance.name);
+					journal.create_substance(custom_substance);
 				}
 			}
 		}
 	}
 
+	if let Some(substance_name) = &args.custom_substance {
+		let custom_substance: Option<psychonaut_journal_types::CustomSubstance> = export_data
+			.custom_substances
+			.into_iter()
+			.find(|substance| substance.name == *substance_name);
+
+		match custom_substance {
+			Some(custom_substance) => {
+				create_or_check_custom_substance(
+					&mut journal,
+					args,
+					Substance::from(Substance {
+						name: custom_substance.name.clone(),
+						description: custom_substance.description.clone(),
+						unit: custom_substance.units,
+					}),
+				);
+			}
+			None => {
+				panic!("Could not find substance with name: {substance_name}")
+			}
+		}
+	} else {
+		for custom_substance in export_data.custom_substances.into_iter() {
+			create_or_check_custom_substance(
+				&mut journal,
+				args,
+				Substance {
+					name: custom_substance.name.clone(),
+					description: custom_substance.description.clone(),
+					unit: custom_substance.units,
+				},
+			);
+		}
+	}
+
 	for experience in export_data.experiences.iter() {
 		for ingestion in experience.ingestions.iter() {
-			let substance_name = mappings
-				.substance_names
-				.get(&ingestion.substance_name)
-				.unwrap_or(&ingestion.substance_name);
+			let substance_name = &ingestion.substance_name;
 
 			let ingestion_unit = match ingestion.custom_unit_id {
 				Some(id) => journal.get_custom_unit(id).unwrap().original_unit,
@@ -111,7 +193,7 @@ pub fn journal_import_psychonaut(
 					}
 				}
 				None => {
-					journal.set_substance(Substance {
+					journal.create_substance(Substance {
 						name: substance_name.clone(),
 						description: "".to_string(),
 						unit: ingestion_unit,
@@ -125,14 +207,20 @@ pub fn journal_import_psychonaut(
 		if journal.first_session_by_title(&experience.title).is_some() {
 			println!("Skipping {} as is already in journal", experience.title);
 			continue;
+		} else {
+			println!("Creating experience {}", experience.title);
 		}
 
 		let session_id = rng.gen::<i32>();
 
-		journal.set_session(Session {
-			id: session_id,
-			..Session::from(experience.clone())
-		});
+		journal.update_session(
+			session_id,
+			Session {
+				id: session_id,
+				..Session::from(experience.clone())
+			},
+			true,
+		);
 
 		let mut ingestions: Vec<Ingestion> = Vec::new();
 		for ingestion in experience.ingestions.iter() {