Hi, In case anyone is missing them, those overloads for to [flat_][multi]set/[multi]map were recently pushed to the develop branch. Since the window for major code changes in the master branch closed at the end of October, if anyone thinks it would be valuable to have them in Boost 1.90, I'd need to ask permission to Marshall. Otherwise they will be generally available in Boost 1.91 (scheduled for April 2026). Best, Ion