So I think the answer for what you’re trying to achieved can be found in these two posts:
and
In a nutshell, you need to specify WHICH form to access, which has as index the same index for the row within which it is nested. To do that you have to:
a) refer to the selected row’s index (if the query is being triggered from outside the expandable row)
b) use i (i.e. form2[i].data) if the query is being triggered from within the expandable row