New UI - Filtering Selector based on two relationships

Hello,

I have the following situation with 3 objects : A, B and C.

A (1:M) B

B (1:1)  C

In a QC page of another object , I have lookup fields to Objects A and C. What I need is filtering the selector page of Object C based on object A. So if for example  i have those links :

A1 has relationships to records B1, B2, B3

and B1 is related to C1

and B2 is related to C2

and B3 is related to C3

what I would need is, on selection of A1 on that QC page, when I will open the selector of C, I want only records C1,C2, C3 to show.

I guess setLookupFilter() wont work as there are two relationships here.

Only way I can think of, is get those records C1,C2,C3 programmaticly,  and filter the grid itself on that selector page.

Any better suggestions? 

Also, how can we filter the grid without accessing DOM elements directly? is there a rollbase method or way to do that?

Cheers,

Meryem