I'd keep checking also. All kinds of times will pop up as people get up and decide to switch parks or not go or are running late and switch their FP to later. I have gotten 4th FP for 4-5 people to Soarin' many times. It will not be nearly as hard as FEA.
But, if nothing closer comes up, I would just go to the CM at the FP scanner, explain the situation, and hope for the best. My son just went with his high school band, and they had this situation probably a half dozen times, and the CM always let them through, including two boys who had expired FoP FP because their bus had gotten to the park late. I personally have also had a CM at FoP allow my daughter and I to go in early with my husband and son. Our FP were for about a half an hour later than theirs. We were totally prepared to wait if she said no, but it was really nice to be able to go together.
If you are polite and aren't trying to scam extra FP out of the system, I think most CM will do their best to accommodate you.