Then do a repeat region on the parent recordset on the page.
After that is applied, manually move the child recordset code inside of the repeat region for the parent.
Now add a repeat region for the child record set inside of the other repeat region.
I did like this but the problem arise that on the child it shows always the same record inside all the parent repeat like as below and not changing the books base on the Cat Name.
Cat Name A
- bookName1
- bookName 2
- bookName 3
Cat Name B
- bookName1
- bookName 2
- bookName 3