If you are using favorites for the people you are following, then I think you could create a template column with the value of email of the person who made the post and the value of “true”, in the posts sheet. In the profile sheet, make another template column that joins the profile user and the value from the isFavorite column. Create a relation column in the posts sheet that joins the template to the template in the profile sheet. Set a filter on the posts list to only show posts where the relation is not empty.