We are installing an attic ladder above our garage. We need a rough opening of 22 1/2", but the ceiling joists are overlapping each other (side by side), so there is only 21" between the joists. Can we cut back part of one of the overlapping joist and add a sister joist to the other side? I am working on uploading a photo or sketch to more clearly illustrate, but if anyone has ideas in the meantime, that would be great. Thanks!