I am trying to create a sheet to resemble tree structure of rows. That is by default all the parent rows must be visible and click of + sign, the row should expand to show its child rows which in turn can have child rows but appear collapsed. When I choose two rows and click on Group and select rows, I see a grouping but when I try to collapse using - sign, both 2 rows gets disabled. I want to make the first row as parent and second row as child. How do I do it?