The client can stop following the current Fusion+ master account by canceling the invitation from the Hub. They can do this by logging on to the fusion hub, clicking on Fusion+, going to my invitation, and turning off the existing invite for the master account.
In order to follow a new master account on Fusion+, the client would need to ask the new fusion+ master to send them a Fusion+ invite.
The client can then accept this invite on their hub and begin following the new fusion+ master account.
Note: Fusion+ copytrading is not available in FM AU.