I am pretty sure you cannot limit the commit to just one record, but you could create a when-list-changed trigger on that first field in the block that checks the :VALUE='Menu' then issues a commit_form.
Whether or not this is possible, I'd say is irrelevant. Auto-committing is an extremely bad idea, especially from a form like this. Sooner or later I guarantee you'll run into a whole heap of problems. Don't do it.