I know there is a out of the box precondition to enforce accepting all incoming changes before delivery. 

Is there a method to change this to accept all incoming changes that are in a snapshot/baseline and exclude the rest?

Users basically want similar behavior to Clearcase where we had the rule to rebase to the recommended Baseline before delivery. Recommending a baseline was predicated on it meeting certain criteria.

In this one project's process, they deliver their change sets to a stream, perform a build and some testing.  At the end of this a baseline is created if all goes goods.  in this scenario, Users would need to accept  Only the change sets in the baselines , which may not be all changesets.