Kaz, we're a bit earlier than you (DS is only 7 months) but have similar things going on here. He was in a solid routine and would be in bed by 7:30pm at the latest, but xmas outings and teething have stuffed that right up. We still try to put him down then, and sometimes he'll go down - but wake up an hour later for some fun time! The first few nights we tried to keep him in his room, re-settle, offer a feed but he was just fighting too hard. So we took his lead, decided for our own sanity to get him up and play until he was ready for bed again. And after that cycle he'd go down for the night.

I feel the same as you - I don't believe they can manipulate us or control their behaviour in such a way and I do believe teeth is the primary cause of the unsettledness here - so we just adjust our approach to keep everyone happy and its working fine.

Good luck