How can I create an additional DDC Farm to load with the same webtop

. I used the iapp F5 Citrix vdi to setup publishing citrix vdi and use the f5 apm as a storefront. I point to a vip address on an internal f5 ltm for the XD controller (DDC). I now want to add an addition DDC farm for resilience. I have added the new vip address for the XD controller to the pool but as this is round robin it will only load one farm at a time. how can i load both DDC farms?