Has anyone been asked to give up a prepaid window or aisle seat in Economy for a middle seat to accommodate a family separated?

This happened to me twice on KLM for a long haul flight to South East Asia. I was approached by a flight attendant asking me to give up the prepaid aisle seat that I had paid for to allow a mother and her child 8 to 12 years to seat together. I would them move to an aisle seat for a flight of 17 hours and not get reimbursed for my seat purchase. I refused and was made to feel guilty by the flight attendants. I was wondering if anyone has experienced this ? I was surprised KLM did not offer an upgrade to anyone who volunteered and were happy to have me waste the money spent for the pre-reserved seat…