To suppress the dialog, you'll need to check the "Perform without dialog" option:
1) You'll probably need to add a Go to Field script step so FileMaker knows which portal it needs to be in. (Go to Object works, too.)
2) Be certain you know which portal row you're in. Otherwise, you might end up editing the wrong related record (which would be Bad). You can put some error trapping in to validate you're on the right record by testing for the value of a related field (such as the related record ID or something).
Thanks Mike. I unchecked the box about the dialog. Why would the dialog box still pop up? It is still forcing me to choose which row to place the Agency Name in. I have tried all 3 go to portal row, go to field, and go to object. The only way I can get it to populate the correct row is to type that row in the dialog.
I can leave it this way, but I wanted to make it fast for user.
What do you have in the calculation? You should leave the box checked, but if it can't resolve the calculation, it still may throw up the dialog.