Do you have a column in your table that identifies those items?
If you don’t, you should add one, and then use that as a filter.
If you show me how your list looks in the Glide Data Editor, I can possibly give some more specific guidance.
This is a little tricky. Can I assume you are working with a Free Plan, and as such don’t have access to the API?
If that’s correct, then your best option is to use the “ParentID reset” trick as described here.