How to help and overcrowded tank?

So, my mother likes to overcrowd her tank. She really likes it over crowded. I tried my hardest to stop it but she went ahead anyways. She wont take any out, or have any less... so please don't tell me to take them out or rehome them, or get her a bigger tank. Because even if I do she'll just fill this one up again and overcrowd both of them. Anyways, it's a 5 gallon with 4 fancy guppies, 6 ghost shrimp, 2 xray tetra's, 2 xray catfish, two pygmy cory's, and a mystery snail. My family also has a wonderful habit of not killing things no matter how bad they are treated. So because they dont die or get sick she doesnt really see the problem. I doubled the filtration and added as many plants as possible. I put in some rocks for increased surface for bacteria to hold too (the rocks are small and dont take up much space)... Any other ideas as to what i could do to make life easier on these fish?