So the minor had no passport going into the country? Is that possible? You can't possibly enter this country with just holding a baby and stating "this is my baby let him/her in." That would create........millions of unknown babies, seriously.
My understanding is you hold on to your I94 no matter what. How did you lose the old passport? In my understanding, they give you the old passport back with your new one along with the I94. In fact, I wouldn't even attach my I94 when getting my passport renewed.