Add_Edit_Sites (bidirectional link to Accounts_Form)

Add_Edit_Contacts (bidirectional link to Accounts_Form)

Add_Edit_Contacts has a Lookup field called "Sites" which looks up site names from Add_Edit_Sites and has a "Set Filter" (see screencap) to filter out only sites with the same account name from the Accounts_Form. 

When adding a new contact from the Add_Edit_Contact and selecting an Account from the lookup dropdown the "Sites" lookup filters only the sites in that Account.

But, when clicking "Add New" when Add_Edit_Contacts is a subform in Accounts_Form the "Sites" lookup is blank/empty (see screencap).

The only way to make the "Sites" field list them from within the subform is by removing the "Set Filter" from the "Sites" field.

Is there a modified way to write the "Sites > Set Filter" to work when it is a part of the Accounts_Form form?

Thanks,

Bryan