if you have access to her computer instead of just her account you could try installing the extension channel block (firefox | chrome). with that you can both block individual channels so that videos from these channels will NEVER EVER show up in sidebar recommendations, search results, subscription feeds, etc. you can also set up regex queries to block videos by title eg. the query “nuke*” will stop video recommendations if the title of the video contains "nuke, “nuclear”, or any other word that starts with “nuke”