How to give relationship 3 or more table without ambiguty

Question

I have 3 tables cust, vend and business table.  

Cust :  Attr grp, cust_num, acc grp, dimension  - relationship  for Cust (Attr grp) to Business (Attr grp) - active working

Vend: Attr grp, cust_num, acc grp, dimension - Relationship for  Vend (Attr grp) to Business (Attr grp) - not working

Business :  Domain, Attr grp, acc grp, dimension, severity (Measure)

How to create a active relationship for these tables?

from Business table - drill through to cust table (on Attr grp)

                            - drill through to vend table (on Attr grp)

How to achieve this with out ambigity in power bi data modeling.