I have created a relationship so that when a user clicks on a button a "new window" (actually another file which through relationships has the same fields as the "original file") opens. The user can then update fields in the "new window" while the original DB stays open in the background...

The problem I am having is that in one area I have several buttons (8) which, when clicked, add a letter to a field in succession (i.e. T,F,L,B,D). In the "new window" file, every time the user clicks on a button it calls an external script and adds the letter- but goes to the original file..

Is there a way when calling an external script that it will do the job in the original file, then return to the "new window" file so that the user can continue to add to the field by clicking buttons?

Put a "Refresh Window [bring to front]" step at the end of each of the scripts to force the desired window forward again.

Why not forget the related file, and make a layout in the original file that looks like a new window.