PIM signaling is supported only in the SD0.
When a PIM join or prune message arrives on the IBBR, the source is resolved only in the SD0 IGP Multi-instance. For example, if SD0 is assigned to MT IPv4-Unicast the source of the PIM message is resolved only in the MT0.
On the EBBR, only SD0 is supported, so if any PIM signaling messages arrive on the EBBR on any other SD other than SD0 they are not processed.
The PIM join attribute uses attribute type 7.