Fortigate 80F WAN to Interface

Good Morning, 

I am looking for information on how I can direct a WAN 1 Interface to interface5/6 with a static IP and WAN 2 to interface 4 with another static IP. Both IP's come from a dynamic IP pool from our ISP. Interface group 5/6 is set to x.x.17.0 and interface 4 is set to x.x.18.0

Is there any way to point these WAN ports to said interfaces without the static IP assignments conflicting and locking down the internet services?