You just need to add a field to your form which saves the original file name.
Have a rule on open which if filename is blank, sets is to your concat (addedtotable, ID). Then in your SP submit use this field as the file name.
On subsequent opens since it has a value the file name will not change.
On your exisitng forms you will need to manually set this since you want to retain the original file name but on any new this solves your issue.
Another option is to query the document library and maybe look for you r user's name if you identify the user and the most recent file they have opened.