Cisco Wireless :: Migrating 2 Standalone 5508 To One Mobility-group

for some reason our wlan-controllers were build up to be standalone instead of beeing one mobility-group. I would like to change this in order to use all features of HA.
 
let me describe our scenario: two WLCs 5508 running SW ver. 6

- same subnet

- both are running in master controller mode

- different hostnames, ip-addresses, etc

- all settings for WLANs and AP-groups (exept the APs themselves in these groups) are the same

- in total at this moment we are running around 100 LAPs configured one half on WLC#1, the other half on WLC#2
 
I don't know exactly why, but when that setting was installed, someone already configuredHA for each accesspoint... e.g.:

- AP#1 primary WLC#1, secondary WLC#2

- AP#2 primary WLC#2, secondary WLC#1 but without WLC#2 knowing the configuration for AP#1 it makes no sense, correct?
 
so my question is: how should I do the migration in the best way?
is it easy as:

- disabling master controller mode on WLC#2

- configuring both WLCs into one mobility group

--> WLCs are negotiating their configurations for the APs