Is a part of deleting Parent and Child relation

[Fusion_Incense]

I have 4 level of Parent & Child relation table,
Which

• Table1(Parent) Table2(Child)
• Table2(Parent) Table3(Child)
• Table3(Parent) Table4(Child)
• Table4(Parent) Table5(Child)

all of those tables I’ve ref. and set "Is a part of " on, here is the problem, when I delete the parent table of table1 only table1 of that Table1ID, and every table2 relate got deleted
but left Table3, Table4, Table5, data that technically still part of Table1. And without the Table1ID existing, those data have no uses
Is there a place I didn’t set up right?