Thanks Mike very kind.
You're right. It look like that, but let me explain:
The fields Tk, Pk, Ck, Fk in the product form are the sum of Tk, Pk, Ck, Fk in product_parts sub_form.
And Tk, Pk, Ck, Fk in product parts sub_form are fields calculation base on data fields in table1, called row_parts...