check name group value
checkbox aaa A 5
checkbox bbb B 10
there are two way to accomplish your task that is....
1) just write on the chekbox checked event of the data gridview ...
DataGridView1.Row([rowinedx]).Cell([cellindex]).ReadOnly=True
2) second is check for checkbox is checked or not on CellClick event of datagridview
and write same
DataGridView1.Row([rowinedx]).Cell([cellindex]).ReadOnly=True
All the best...............