I had the same situation as LW2 at my small restaurant wedding reception.  My parents paid for it, and were very poor at the time, but insisted on paying.  We invited only a few close family members, as it was out of state.  When my mother stipulated no kids, my sister-in-law, who had 4 young kids, said she would not attend.  Since my husband was very close to his brother, this caused a rift, and my parents had no choice, they thought, but to bow to SIL’s demands.  When dinner was finished, I excused myself to run to the rest room, and when I came back out to the restaurant lobby, SIL and family had left.  They hadn’t even stayed to say goodbye and good luck.  We were heading back home and wouldn’t seem them again.  I never felt the same about SIL again, where previously, I liked her.  Fortunately, we lived across country, so saw them rarely.  I like Amy’s reply that that the couple stand strong and stick by their no-kids request.  It’s their reception.