lacp on 148poe configuration with proxmox

Hello.

I'm moving away from a HP switch (no cli access) and a Sonicwall firewall to the Fortigate side.

I have a 91G and 2x148fpoe switches connected.  They are currently configured in Fortiilink and managed so all ports are being managed from the 91G.

I have 2 Proxmox servers that I will be moving over to the new environment and am trying to understand how LACP/LAG works on the Fortigate.  It seems similar with Active/passive mode and 'bonding' 2/or more interfaces into the same LAG group so traffic can travel across both if/when needed. 

I'm trying to understand, and it seems like I would do the following:

1. Open the fortiswitch ports tab

2. Choose Trunk ports

3. Give it a name and add ports either from the same switch, or specific ports on different switches.

4. Set the mode to 'active' and hit 'ok'.

If I'm thinking correctly then this would set up, say port 1 on sw1 with port2 on sw2, in a LAG/LACP group as active.  Correct?

Is that all there is to it, since the 91G is managing both switches? Is my 'choice' of using a port on 2 different switches a good idea?

Then, if I have my Proxmox box set correctly - all should work.

thanks in advance.

mark