IPv6---About NeighborSolicitation and NeighborAdvertisment

Generally after node sends NeighborSolicitation Message, other nodes
will send NeighborAdvertisement Message. But if the node's MAC
address has been changed, node will send NeighborAdvertisement Message
initiatively.
In my case, tester sends NeighborAdvertisement Message to a router
initiatively and then sends RouterAdvertisement Message to the router
initiatively.

I am not clear about:
What will happen to the router?
Which type of Message will be sent by the router?

Thank you!