Wireless controller AP migration

Recently I did a wireless AP migration from dual WLC5508 to dual WLC5520. There is not a lot of documentation out there on preference options for access points to join the controllers eg DNS, DHCP etc.
To create a pilot group on the new WLC, we were able to tell some access points to join a specific controller. In the access point High Availability options you have to specify the name of the preferred WLC and IP address.

Cisco Wireless peer to peer blocking

Recently I was working on an issue where wireless clients on the corporate wireless network were unable to communicate with PCs on the corporate wired LAN. Peer to peer blocking is applied to individual WLANs. You can have traffic bridged locally within the controller, dropped by the controller, or forwarded to the upstream vlan.

In order for this to work, under WLANs on the WLAN Controller, select the required WLAN and select the Advanced tab. In the P2P blocking action drop down menu I changed the setting from drop to disabled. This changed from the controller dropping the packets to disabling P2P blocking and in turn, bridges traffic locally.