Inserting a profile into a projected profile

I have an FM road that I have an existing profile created using the "Quick Profile from Surface".  The job entails planning 2" then adding a 2" ACP overlay, therefore the proposed profile will be the same as the existing.  There are gaps at the bridges.  I have one bridge replacement that I am creating a 400' length proposed profile.  How do I merge this proposed profile with the first proposed profile (from the surface)?