FortiGate + FortiSwitch - Ports don't intergrate. Am I missing something?

I've been using Fortigate for years, finally got a Fortisiwtch to add to my system, and it doesn't do what I thought it did.  Maybe I am missing something, so I thought I'd post here to see. (support was no help).

When you add a Fortiswitch to a Fortigate, it does not give you more ports to work with, it gives you a DIFFERENT set of ports to work with.

In my setup, I have a bunch of VLANS - I then have a few physical ports on the firewall that are VLAN trunk ports (all the VLANs are beneath it).  I currently run those ports to some HP switches where I can then trunk to a server or send a specific vlan.

I assumed adding a fortiswitch would allow me to do the same, but I can't.   The fortiswitch REQUIRES me to make a new set of VLANS  - they can use the same TAGS, but will not talk to the Fortgate VLANS.  The new Switch VLANS can ONLY be used in rules, and not in anything like a software switch.   So no linking to existing networks, requires all new IP ranges. Can't link a SSID.

I'm almost thinking I need to run 2 cables from the FG to the FS - 1 for control, and one as a VLAN trunk and just use the common GUI for ease of management, but treat them as 2 separate systems.

Does anyone have any better ideas?