oracle Table partition with purging by insert into table using filter conditions

We are looking for partitioning a parent table which has more than 30 child tables.We are planning to create a new table structure and insert data using select from original table.

Select from original table will also be filtered based on some conditions , this would achieve data purging. But the issue is child data , how to we get rid of that as well to aviod parent key now found errors for child tables.