You can convert an existing inventory item into an assembly item directly from the item list in ConnectStock.
Steps
Go to the item list in ConnectStock.
Click the 3 dot menu next to the item you want to convert.
Select Convert to Assembly.
Requirements
Turn on Assembly Items in File Settings, General. Go to Stores & Files, then Inventory Files, and click your inventory file. Click General, click Edit, turn on Assembly Items, then click Save.
Only an inventory item that is not already part of an assembly can be converted. If the item is already used as a component in an existing assembly, it cannot be converted, since it is tied to a different assembly.
You also can't convert an item that is used in an active assembly build or disassembly.
Frequently asked questions
Why don't I see Convert to Assembly?
Make sure Assembly Items is turned on in File Settings, General.
Why can't I convert my item?
The item is a component in another assembly, or it is used in an active assembly build or disassembly.