How to confront multiple sheets against each other?

English is not my first language, if anything doesn't make sense pls ask.

I am currently trying to filter a bigger excel for a conference programm, their file was divided as such sheets:

Day 1, Day 2, Day 3, Day 4 -> this containes, for each day in the title of the sheet each conference title for a given room at a given time.

I created other sheets, which i named as the main topic.

for example: Hybrid if the sheets containes mentions of hybrid as a word in the session or title of the conference.

I am now stuck, since I only searched my main interest and created new sheets only for the word I choose. I now have a incomplete subdivision, since I didn't copy each and every conference.

I would like to create a new sheets named OTHERS in which I import any conference I don't have in the specific sheets I created.

So for example if in Day 1, row7 column 15 never appear in each new sheets I created (hybrid, liquid, ...) I want that row imported in the sheets OTHERS.

Is there a way to do this, even only by finding the single row# column# and then I can manually create the table for the new sheets OTHERS. Or I just need to filter manually or use an AI (which i don't like to do since I want to use excel if possible)