How to set property in each row of a child table?

Suppose I have a template table with this data
name: a, row:1, options: 1\n2\n3
name: a, row:2, options: 4\n5\n6
I want when I choose template with name: a in a doctype, the child table in that doctype will have two rows, and for the first row will have a select field with option 1,2,3, and the second row will have select field with option 4,5,6