RECNO NAME DATE OF BIRTH ADDRESS 1 father_a Oldest a_city <- Select 2 mother_a a_city 3 son_a a_city 4 daughter_b b_city 5 grandmother_b Oldest b_city <- Select 6 mother_c Oldest c_city <- SelectI need to send ONLY ONE letter to every family that the member is the oldest, and all members of a family have the same address. So RECNO 1, 5 & 6 are selected.