Older kids

Our 5 year old foster son (whom we hope to adopt) attends religious school at our synagogue, which he loves. We say blessings at dinner every day, light shabbat candles, generally live a Jewish life. As we attend a reform synagogue, we had not planned to have a conversion for any children we adopt at an older age and just leave that to the B'nai Mitzvah. But we have been thinking about Jewish names and it might be nice to have some sort of ceremony when we adopt him, welcoming him officially (other than the one on Simcha Torah when he was welcomed with the other kids starting school). Has anyone done something like this for an older child? Have any ideas or suggestions?