First, I never decline a meeting without offering option(s) and with reference to managing the conflicts I would reach out to learn if some or part of the meeting may be condensed, if a substitute would make sense in certain situations or if the agenda allowed for the person that needs to attend to possibly attend a portion. In addition, if the possibility of any of the above does not facilitate scheduling, suggest one / one meeting to update with key points / takeaways. Any of the above can combined.