Aviv,
The Dynamic VC feature allows for automatic failover between several potential VCs. The election is based on the RF Domain Manager process, where the most powerful AP model wins. If the candidates are of the same model (recommended) then the one with the lowest MIND ID wins.
This can be modified by setting the rf-domain-manager priority value in the AP's SELF section.
So, if you have two AP8533 that are VC candidates, giving the one you want as Master a higher priority should do the trick:
ap8533 B8-50-01-17-8C-90
virtual-controller
virtual-controller auto
virtual-controller management-interface ip address 172.16.3.99/24
rf-domain-manager capable
rf-domain-manager priority 100
ap8533 B8-50-01-2C-35-A0
virtual-controller
virtual-controller auto
virtual-controller management-interface ip address 172.16.3.99/24
rf-domain-manager capable
rf-domain-manager priority 10