I think the question should be, why do you want these VM's to run on the 3th host? The idea behind a cluster is a shared pool of resources, which can be used by all VM's in the cluster. If no resource contention is detected, the VM will keep running on the host it is placed on, even after a vSphere HA failover.
If for some reason, these VM's need to run on the 3th host, and you have enabled vSphere DRS on the cluster, you can use affinity rules to specify where VM's should run and if VM's providing the same service should be spread across different hosts. Using DRS Affinity Rules