XG-7100 pair LACP WAN

[sipple31]

So I understand that from a pfSense standpoint the interfaces are just VLANs into the switch.  I need to have LACP enabled on the WAN port on my HA pair (because upstream is a pair of edge routers running MC-LAG).  How would I go about doing that?  Under interfaces / switch / LAGGs - I cannot create a new one.

thanks!  8)