Parent and child doctype problem

I am new in erpnext.

I create the webform and store the value in doctype. Now the individual fields value stored in the doctype but the problem is the table value not stored in the doctype. I create the child doctype and specify it in parent doctype.

The child doctype columns are shown successfully in the webform but the values didn’t store in the parent doctype.

My another doubt is, I create the single column in the child doctype in gridview. But in the webform the table value added extra one column (name field). Normally its not show but when i was click the editing row its shows extra one column.

Here some screenshot about this problem.