In coming up with a novel solution to solve another long-standing CRM issue (not being able to use variables in subgrid views), I'm using out of the box N:N relationships and subgrids on the account and contact entities along with some other rudimentary wizardry to associate and disassociate records (cases, opportunities, orders, quotes) created within the context of 1:N relationships. It's working great - now I can see Orders related to Accounts across multiple relationships in a single N:N subgrid.
My issue is that the + Add New button isn't displayed in the UCI when selecting Only Related Records, and using the +New option in the Add Existing pane fails to preserve any relationship mapping. See Below:
Adding new in the legacy/web interface:
1 - Click +New from the N:N Accounts:Salesorder subgrid
2 - The Account gets populated on the resulting Salesorder record:
Adding new in the UCI:
1 - Click Add Existing from the subgrid
2 - Click +New on the Add Existing pane
3 - The new record has no relationship mapping
So the question is - how do we either 1) enable the AddNewStandard button on N:N subgrids in the UCI OR 2) preserve the relationship mappings when creating a new record through the Add Existing route? I've been poking around in Ribbon Workbench and can't seem to make any progress.