I finally set up the Trail-a-bike I bought second-hand for Gemma yesterday. What a triumph! She caught on straight away and was pedaling like a fiend. It was a bit fiddly to attach to my slightly-oversized seat post, but I got it on there in the end.
I also got Elsie's free-on-curb bike seat set up on Kim's new bike, and she was equally thrilled. We had a nice family ride around the neighborhood to celebrate.