I still think that LIS-PHL-DFW could be the best option here. Is the Saturday of Thanksgiving weekend a busy day for inbound international traffic? If not, then getting through Immigration and Customs at PHL should not be too bad, and I am guessing that the OP could utilize the MPC app for his entire family. With young kids in tow, I also think that it's better to get Immigration and Customs out of the way sooner rather than later.

It's true that IROPS could cause a problem getting from PHL to DFW, but AA has several daily PHL-DFW nonstops; whether four seats on a single later nonstop could be found is a legitimate concern.