After I create a relationship, and Press the Add button. Is there a way to retain information from the previous form.

A simple solution could be to use ADD Similar.  When you save the record, I assume that it display the record back to you.  If you clcik ADD Similar it will add a similar record.  You flag each field in field properties as to if uyou want themk to carry formard on an Add Similar.  So you would need to edit the field properties for all all the fields that you do not want to carry forward, as the default is to carry forward.

Look for the checkbox

"Copy this field's value when clicking the "Add Similar" button to add a new Record"

Markl Shnier

Assuming "Location" is the name of the field in the source record that you want to use as the value for FID 7 in the new record, you want modify what you have to be:   "?a=API_GenAddRecordForm&_fid_7=" & URLEncode([Location])

Since in your original line, you have the field within the quotes, it isn't inserting the value of that field, it is just literally including that string of characters.    I put in a URLEncode so that it will handle special characters like spaces, dashes, etc. if they are part of the Location value.

Hope that helps,  Keira