I had 3 out of 4 children by c-section. I was told my flap was because of scar tissue adhesion and I was told I could massage it each day to try to avoid it adhering after my last c-section. Ummm heck no that hurts.
When I went from 240 to 165 the flat did get smaller but never went away completely. I am sure if I lost some more weight it would have been more or less gone but there would always be that line that was stuck and any excess fat would hang over it.
A lot of people I know are swearing by those It Works wrap things for Mommy tummy.