Help with vlan failover trunk

[tem8888]

Hello. I have some project with configuring Fortigate 100E there couple of Vlan networks, main task is make checking life of main link with link monitor or some similar protocol. to control link for example with main server 192.168.1.1 if its working or not, and if its fail switch to secondary link. also problem is that I have no access to switches and cant make changes on them. and second issues is to make transparent Vlan networks 2.x,3.x to become failover.Maybe there some protocol for make monitoring and switch channels on/off ports for example...network sample scheme in image below.Thank you for advice