How about an option to overwrite on a per-line basis? Add a +replace_line, then the next entry will be completely overwritten. If you want to erase an entry, for example have the $Default PBanks: line erased, just leave all the info from the line, basically everything you'd put in after the ":", blank. Under this proposed code, it would let the computer know to completely erase the $Default PBanks: line. On the other hand, if you're worried about the ship flags, the +replace_line use would let the game know to dump all previously present flags, and use ONLY the ones listed in the tbm.