Yeah, we don't get this request very often ... "please fail over slowly" .
So, you will have to be more specific with at which point you want to fail back over ... what is the trigger that defines you are ready to fail over.
If this can only be "known" via manual diagnosis or analysis, then you must revert to a manual fail over mechanism (such as keeping your peer in a shutdown state until you "no shut" it).
If you want this to happen automatically, based on some trigger, then you have to define what that trigger is, so that the router can be programed to act on that trigger.
Rob