Managing FortiAPs and FortiSwitches accross segments via Fortigate

[Qubit]

Greetings All! I need your expert advice and  guidance. I have an MPLS network with 10 different sites linked by Cisco Routers with all of them breaking out to the internet via datacentre through the 500D. All hosts can communicate with with each other from all sites/segments and I can access the 500D from within the network from all segments. I have purchased  20 x 224DFPOE Switches and 15 x 320C AP and I plan to deploy these to my sites.Eventually I would like to manage all of these devices via my 500D. My understanding is that in order to manage these devices I need to setup a Fortilink. I've read a few articles as well as watch a few videos on how to setup up the switches/AP but it seems on all the resources I come across there has to be a direct physical connection from either the Switch or AP to the FortiGate. For someone in my scenario where all of the APs and Switches will be sitting at different sites/segments but can communicate internally with the FortiGate, is it possible to link them?  I understand that one can setup a logical Fortilink interface but I don't know if this is how one does this, I would highly appreciate any feedback in this regard. Cheers!