I mean it’s a bit unclear what you’re asking ? Which logical unit ? There are many ways to answer your question, the use case isn’t clear.

You attach a document in either line or header exactly the same way all over the application, but the logical unit needs to be enabled for Object Connection for service DocReferenceObject

This for instance would mean that you can attach a document on both the Customer Order Header, and on the Customer Order Line.

(Note that adding an Object Connection requires then refreshing the ObjectConnection Cache, and users will likely need to log out and back in before they can see the option to attach a document)

If you’re asking that a document attached to the Header automatically appear on all lines (and/or vice versa), you do that through Object Connection Transformations

The above for instance would make it so that any document attached on the CustomerOrderHeader also automatically appears on Customer Order Lines

Hi @SimonTestard 

Thank you for your help.

Very helpful.

Regards

Haro.