Assignment Rule Condition for Child Tables

Good day. I want to ask for help with regard to the new Assignment Rule in ERPnext (version 13). I was trying to use data from the child table for my auto assigning but the ‘for’ under python doesn’t seem to be working. I also saw that child tables can be chosen when making the assignment rule but when you click those, it doesn’t seem to work on the parent doctype.

Is it possible to use assignment rule for the child table? or is it only meant for the parent doctype?

By the way, I was able to find a way to do it but it is quite tedious since it requires every line or every number item to be placed in the code. I don’t see this as an appropriate solution since it requires every line item to be placed.

items[0].item_group.find(‘X’) == 0 or items[1].item_group.find(‘X’) == 0

Thank you.