No harsh words coming from here! I think we can all relate very well. I have thin cats that need to eat because they are very young and active and then I have a few who are getting older and starting to put on the extra pounds. I have no idea how to handle the whole thing either. The thin ones eat very small amounts but periodically through out the day and the heavier ones really don't eat that much but are just older and heavier (I can understand how that happens!) Magoo is really packing it on and I need to get a handle on him now because he is getting huge! He doesn't eat that much either and I think a lot of his is because he was recently nuetered. I have cut way back on his treats because in the beginning I felt so sorry for him since I knew he had been hungry for so long.
As we all know they can make your life miserable when they don't get what they want!!! With the multi cat situation I don't know what to do either. I think for me I'm going to wait just a little longer to let the youngsters get another year older and then I'm going to switch food and see if that helps. I'm feeding so many though I can't afford anything very expensive.
It is a very trying situation isn't it? Maybe you could find some health food treats that would be good for her and try those instead. I wish I was more help but I'm in the same situation!!