diff --git a/src/schemas/inventory/purchaseorder.schema.js b/src/schemas/inventory/purchaseorder.schema.js
new file mode 100644
index 0000000..4925571
--- /dev/null
+++ b/src/schemas/inventory/purchaseorder.schema.js
@@ -0,0 +1,44 @@
+import mongoose from 'mongoose';
+import { generateId } from '../../utils.js';
+const { Schema } = mongoose;
+
+const purchaseOrderSchema = new Schema(
+  {
+    _reference: { type: String, default: () => generateId()() },
+    value: { type: Number, required: true },
+    unit: { type: String, required: true },
+    parent: {
+      type: Schema.Types.ObjectId,
+      refPath: 'parentType',
+      required: true,
+    },
+    parentType: {
+      type: String,
+      required: true,
+      enum: ['filamentStock', 'partStock', 'productStock'], // Add other models as needed
+    },
+    owner: {
+      type: Schema.Types.ObjectId,
+      refPath: 'ownerType',
+      required: true,
+    },
+    ownerType: {
+      type: String,
+      required: true,
+      enum: ['user', 'subJob', 'stockAudit'],
+    },
+    timestamp: { type: Date, default: Date.now },
+  },
+  { timestamps: true }
+);
+
+// Add virtual id getter
+purchaseOrderSchema.virtual('id').get(function () {
+  return this._id;
+});
+
+// Configure JSON serialization to include virtuals
+purchaseOrderSchema.set('toJSON', { virtuals: true });
+
+// Create and export the model
+export const purchaseOrderModel = mongoose.model('purchaseOrder', purchaseOrderSchema);
diff --git a/src/schemas/management/documentprinter.schema.js b/src/schemas/management/documentprinter.schema.js
index 1ccbea1..f3bbf6b 100644
--- a/src/schemas/management/documentprinter.schema.js
+++ b/src/schemas/management/documentprinter.schema.js
@@ -32,6 +32,7 @@ const documentPrinterSchema = new Schema(
     },
     connectedAt: { type: Date, default: null },
     host: { type: Schema.Types.ObjectId, ref: 'host', required: true },
+    vendor: { type: Schema.Types.ObjectId, ref: 'vendor', required: false },
     queue: [{ type: Schema.Types.ObjectId, ref: 'documentJob', required: false }],
   },
   { timestamps: true }
diff --git a/src/schemas/production/job.schema.js b/src/schemas/production/job.schema.js
index b8ad125..78f484a 100644
--- a/src/schemas/production/job.schema.js
+++ b/src/schemas/production/job.schema.js
@@ -12,8 +12,8 @@ const jobSchema = new mongoose.Schema(
     printers: [{ type: Schema.Types.ObjectId, ref: 'printer', required: false }],
     createdAt: { required: true, type: Date },
     updatedAt: { required: true, type: Date },
-    startedAt: { required: false, type: Date },
-    finishedAt: { required: false, type: Date },
+    startedAt: { required: false, type: Date, default: null },
+    finishedAt: { required: false, type: Date, default: null },
     gcodeFile: {
       type: Schema.Types.ObjectId,
       ref: 'gcodeFile',
diff --git a/src/schemas/production/subjob.schema.js b/src/schemas/production/subjob.schema.js
index 5447088..adbae06 100644
--- a/src/schemas/production/subjob.schema.js
+++ b/src/schemas/production/subjob.schema.js
@@ -39,8 +39,8 @@ const subJobSchema = new mongoose.Schema({
     type: Date,
     default: Date.now,
   },
-  startedAt: { required: false, type: Date },
-  finishedAt: { required: false, type: Date },
+  startedAt: { required: false, type: Date, default: null },
+  finishedAt: { required: false, type: Date, default: null },
 });
 
 subJobSchema.virtual('id').get(function () {