Exposed filters must be shown only on one term with children

Hi all,

I have next situation:
Vocabulary X with terms
X
-1
--a
--b
--c
-2
--d
--f
--g
--h
-3
--i
I have 2 exposed filters, which I want to show only on -2 level and children, not on -1 level and -3 level.
How to achieve this?