Answer: piggybacking

AnswerCrossword Clue
PIGGYBACKINGRiding on someone else's shoulders
piggybackingCarry by or as if by piggyback
piggybackingMount on or attach to (an existing object or system)
piggybackingUse existing work or an existing product as a basis or support
piggybackingPIGGYBACK, to carry someone on one's back also PICKABACK, PICKAPACK, PICKBACK