It would appear that booking individual round trips for each of you is the proper route. As US Airways flying from PVD to PHL it would seem easiest to have your daughter fly to PHL and then meet you at the airport. Allowing for a moderate amount of time between flights for any possible delays or having her fly in a day or so before and then return together with her flying on to PVD. As for pricing that depends on when you book and when you're flying.