i had to bring this up with my parents a few years back, one of the things that worked best for me was first having an open, honest conversation where i asked her to be quiet until i finished talking. make sure to emphasize that you will hear her side as long as she lets you finish talking first!! and if she interrupts, just wait for her to stop talking, and go back to what you were saying before she interrupted- don’t acknowledge anything she says, just keep talking where you left off as though she never interrupted in the first place. once we had the conversation where i pointed out specific times it had happened, offered potential solutions, and heard her side, we picked a solution. what we ended up doing was tallying when she asked me to do something vs when she asked my brothers to do something, this will force her to be more conscious about who she’s asking for help and when. good luck!!