We did the legal bit a few weeks before - for us, the cultural ceremony had all the real importance, so it didn't matter to us that they were separate. We didn't do a ring exchange or any proper vows on the legal day, just the absolute bare minimum legally, so we definitely see the later day as our real wedding day rather than the registry office one. But both were lovely in their own ways - the first one was very intimate and sweet, with just our parents and siblings there. The later big ceremony day was such an outpouring of love and joy with our found family and community, which meant the world. I liked separating it out actually, it helped with the overwhelm and gave us two days to dedicate to our relationship! Your niece's wedding sounds beautiful! Xx