Compress kerning deletes exceptions

If I understand correctly the compress function in the kerning window is supposed to delete unnecessary kerning pairs, for example when adding classes later on. Unfortunately it deletes also exceptions. For instance I have the kerning pair tcaron question. When I later add any class, and run the compress function, it also closes the lock of tcaron question, so suddenly t question also has kerning (which it shouldn’t). Is there a way to keep this exceptions?

If you tell me how to differentiate between the different pairs? How should glyphs know what an exception ist and what not. The only way is to add default zero class kerning (for @t - question).

Ok, I understand. Thanks, Georg.