Solution 1: operational solution

1-1 Always use linklocal nexthop in MRIB
1-2 Assignes RP address on a separate interface 
so that the global prefix should not be shared
e.g. assign a separate address on loopback IF

Pro
no need to change the PIM protocol / implementations

Cons
increase operational cost
cannot assign global upstream address
need to advertise a particular host route
reduce operational flexibility