How to add extension field in Outbound Deliveries to the Customer Invoice form template Layout.
You need to first extend the extension field from Outbound delivery to Customer invoice request using adaptation mode -> Extension Scenario. Outbound Delivery - General Information to Invoice Requests - General Information.
After that from invoice request screen you need to extend the same field from invoice request to Invoice via adaptation mode -> Extension Scenario.. Invoice Requests - General Information to Customer Invoice - General Information.
Then from Invoice Screen, you can extend the field to form template via adaptation mode -> Form Templates.
You can refer to the "KBA 2905703 - How to Work with Extension Scenarios" to extend the extension field to multiple screens. And refer the "KBA 1764460 - How to Add Extension Field in the From Templates?" to extend the extension field to form template.
Thanks & Regards,
Arjun T H
SAP Product Support