[phenixbb] constrain insertion codes to unit occupancy?

Hi: I’m refining a site where there’s two compounds, each at partial occupancy. I modeled that using alt codes and insertion codes combined, like this ATOM 6500 CA ACYS B 101B ATOM 6490 CA BXXX B 101A How can I constrain the occupancies so that they sum to unity? I tried several option, but the distinct insertions seem to refine independently. Sorry if a similar question has been posted before, but I could not find a solution searching phenixbb. Thanks! Henry