Custom Bind for textbox (itemtemplate)

[Cheng]

hi everyone,
I created a nested gridview.

1.In child gridview there is a itemtemplate (texbox) called "amount".
2.and one column in child grid view is called "SbaAmount".
3.a column called "MdlAmount" is in the parent gridview.

Now the problem is the value in the "amount" should be "SbaAmount" *
"MdlAmount". How can I do this? use custom bind?

Context:
The child gridview is in the edittemplate, when I click "edit" in
parent gridview, the EditIndex will be recorded in session and the
session is the parameter of the sqldatasourse for child gridview.

can i get current row index without using editindex? therefore i can
show all child gridview i each row without click "edit".

Regards
Cheng