I'm having a problem on how to fetch the data of parent then display the child from different module

Hello Everyone, I’m having trouble on how to fetch the all item group. The categories here on all item groups should be displayed on the second picture which is the custom_item_group. The data child inside the parent should be displayed on the table (third picture).

When I click the item code it should be filtered depends on what I selected on the custom_item_group field. Can someone help me with this problem? I’m stuck here.

I only see one attached image, so your question is missing data.