First get the 225s on another VLAN (not the one with your production VC) , then match the InstantOS installed on your 105 Cluster and then maken make one of the IAP105s your Preffered Master after that you can move the 225s that you want to be part of your current cluster.
After those are part of the cluster then you can build a mesh link between the IAP225 and IAP105's, and then remove the Preferred Master option from one of your IAP105s
To build another Cluster you just need to place the new IAPs in a new VLAN and those will form their own cluster