Help with New Record and Add Record Buttons

I have a table that is related to itself. Some records will be parent records and some will be children of the parent records.

I would like the (green) +New Record button to open a form I created for the parent record (form id 2).

I would like the "Add  Record" button to open a form I created for the child record (form id 10).

After researching, I've found that this formula should work, however it is not. Both buttons (+New Record and Add Record) are both launching the Parent Form. 

This is the formula I'm using for the Add Record button:

URLRoot() & "db/" & [_DBID_TEST_TABLE] & "?a=API_GenAddRecordForm&_fid_18=" & URLEncode ([Record ID#])& "&z=" & Rurl() & "dfid=10"

I suspect it isn't working because of the Role settings. I can only select one form for each role. I need two. Users need to be able to enter a parent record using the +New Record button (launching the form for parent records) and add a child record using the Add Record button (launching the form for child records)

Is this possible? Any help/guidance/ideas would be appreciated.

Thank you!