I realize that the following flights are UA flights... but I've put it here in the AC forum since I'm an AP-E and it's the concept that I'm looking for clarification on.

I'm looking at booking the following routing:
TPA - BHM via CLT (segments 1,2)
BHM - GRR via ORD (segments 3,4)
GRR - TPA via ORD (segments 5,6)

My question involves skipping flight segments during the routing. I understand from reading other threads that you can't skip the first flight in a leg, as it would cancel the rest of the legs bookings... but what about skipping one in the middle?

Specifically, I'm thinking of skipping the flight from ORD to GRR (i.e. the fourth flight) and making my own way to GRR after spending some time in ORD.

If I skip this flight, will my ticket/reservation for the return from GRR-ORD-TPA still be valid?