It’s a violation of both FAR’s and airline policies. No child under 15 may be seated in an emergency exit row. No lap children, obviously. Most airlines, mine included, will not allow separated families to occupy exit seats. Dad can’t take the exit while mom and kids sit two rows back. It should be covered when seats are assigned. In my case, we are to ensure this doesn’t happen. On its surface, and without seeing everything personally, it seems to have been a failure on the part of the flight attendants.