List of VALID options for Custom Forms

I simply want to add the

ITEM Supplier in the Bom explosion view (Printable Document)

Since it’s not included By default on the Bom Explosion Form, I have to add it.
If I got the right entry to fetch the item supplier out of every item in the list, then It should be easy.

I’m trying to keep the setup as stock as possible.

I’ve been able to add some infos and fields in other forms without any problem using obvious logic. But for the item supplier, Default supplier, it sound like it needs a twist.

Thanks

Prod