I set a custom form and tree view to party.party without inherit it.
I added a many2one field to a different model.
When add the field into the view xml file I set which views should use:
<field name="many2one_field" mode="form,tree"
Unfortunately It's loads the original party view form (from party module) and do not loads the custom party view form (from custom module).
How to reproduce:
1. Click on magnifying glass on many2one custom field.
2. Click New button
Something that is working, is that the tree view that it's displayed (when click on magnifying glass) it's from the custom tree view.