How to bind values on data grid view empty cells using c# wi

Hello Sir,

I am creating windows application c# 2010, here i am explaining my project details anyone solve my problem sir.

I am using 2 two dropdown list

i am select first dropdown list that time values are displayed on my data grid view with some empty rows.

check my image link sir.

http://www.cubicsoft.in/demo/fir-binding.jpg

After that i am select 2nd drop down list

that time i want records update on my empty row cells.

this is my second image link sir,

http://www.cubicsoft.in/demo/Second-explain.jpg

But not fixed for 3rd and 4th rows are empty, some times 6th, 7th and 8th rows are empty.

How to create my logic sir, give me some help sir,