Load Balancing / Failover for specific VLANS

Hi,

I had zero luck with Fortinet support, so I thought maybe someone here could help.  I have a Forigate 80C v5.25 build 701 configured for WAN Link load balancing:

Weighted Round Robin

wan1 100% (primary ISP)

wan2 0% (backup ISP)

This is setup so that if primary internet goes down, failover will occur and wan2 will take over

BUT I only want certain critical VLANS to be enabled when failover occurs.

I would think I'd be able to edit my policies and choose wan1 or wan2 as Incoming Interface but wan1 and wan2 are not options, only the virtual wan load balancing interface I created.

Is there a way to do what I need to do?

Thanks,

BD