Power BI data model in SSAS

I am in the process of replicating a power BI model in SSAS and then do an import. I have three tables A, B and C. B is a bridge table and I am trying to bring columns from C to A. In power BI I used the merge query option to bring in the columns. How to do it in SSAS? 

I used the RELATED(C.x)  and LOOKUPVALUE (C.x, C.id, RELATED(B.id)) dax queries but it's not working. Can anyone please help?