If you put it on Mom, she'll be more compliant and end up 100 % sub no matter what, she'll allow herself to be raped before you push her there, and it will change some scene descriptions (mainly make your sister way more dominant in threesomes). If you are submissive when attempting to put it on her, you'll end up with it yourself, and be essentially locked into sub, it will cause some bodily changes like dick shrinking and ass becoming more accommodating (even removing your virginity if you never get fucked). Some scenes will change that you will end up automatically bottom or getting dragged along or having no way to resist things you otherwise could.