Multicast issue in NBMA

Hello expert. I'm having a challenge with a certain scenario. Say we have 3
routers(R1,R2 and R3) with R1 as the hub (in a frame relay network with
ospf network type "BROADCAST") while R2 and R3 are spoke routers.

All interfaces are in sparse mode. Now,I have a host behind R2 trying to
join a multicast group whose RP is on the loopback(3.3.3.3/32) of the other
spoke router,R3.

Now,the issue I'm encountering is that R2 gets the join message and has an
entry for (*,G) but R1 isn't getting the join message neither does it have
an entry for (*,G).

You assume all the routers are connected to the FRS using their Serial1/0
with IP addresses 10.10.10.(1,2,3) for R1,R2 and R3 respectively.

What I'm assuming might be the problem is that fact that the next hop and
RPF neighbor indicated on R2 for the RP address is 10.10.10.3..Now this is
expected since it's an OSPF "broadcast" network type and they are all in
the same broadcast domain.

P.S Each spoke router has a frame-relay map statements to both the hub and
the spoke routers.

Thank you.

-- 
Warm wishes,
Ty.
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