What if during an extended bread meal there was a time in that meal of maybe 72 minutes where they weren’t sure they ate or drank in the middle? Like they got up to read Torah and lost track of the time. Can they still recite Birkat HaMazon?
yes they still can. The reason is because we can say birkas hamazon until we still satified from the previous meal, even if it is more than 72 minutes.
Gmar chasima tova