C7 \ AbMaj = C7 (#9 b13)
C7 \ BbMaj = C11 (#13)
C7 \ Em7b5 = C9 (#13)
These are usually used in specific places, because of the 13th. I'll write out some examples with each later. It's 5am here. I need to go to bed.
....Adding to this: It's very easy to identify chord names, if you have the numbering system down. Also, every chord can be called something else, because since there are only 12 notes, the same notes could make up a different chord, if inverted. That's how you get direct substitutions.