Transaction Processing Form Interconnect on Row Exit

[BOster]

Is it possible to extend a transaction boundary from Form A to Form B using a Form Interconnect on a Row Exit?

Here is the situation:
Form A is Headerless Detail.
Form B is Headerless Detail.

User enters record in Form A, selects record and clicks row exit to Form B. Enters records in Form B and clicks OK, but clicks cancel in Form A. Form B records are now orphaned.

I can't seem to solve this using Trans. Processing. It looks like you can only extend a Trans boundary on a form interconnect in the OK or Cancel button of Form A.

What am I missing?

 

[Mu Bo]

I would like to hide row exit menu until saving that row, and also disable the foreign key(s) after saving, then exit to form B.
Please check ECO Parts List (P3013) row exit "related parts" for reference.