If you duplicate the album (i.e. highlight it in the left-hand tree, then go to 'Tools' menu, then 'duplicate album'), you will get an exact copy of the record except with a "2" in brackets after the title. This duplicate will not have the 'add/subtract tracks' options greyed out. What I do is make my changes, then delete the original album, then remove the "2" from the revised entry.

Does this help?!