I have done this with Master PVDProf several times, albeit on UA. Sometimes I bothered to use multi-city to guarantee the routing (UA doesn't require 4 hour stopover, just make sure there's an O rather than X in the fare construction), but other times I decided to absorb the risk that there might be irrops and I wouldn't be able to request a reroute through the airport I at which I met the grandparents.

My parents were always able to get a gate pass to meet me, so you wouldn't need to worry about security.