Multihomed routing, vpn and all all all. How to implement?

Question

openvpn

there is such a network diagram.
Currently done in freebsd+pf. Channels on the Internet change according to the principle of performance (the main one fell, we raise the reserve) and openvpn calls back to a live one from remote addresses.
And I would like the scheme to work like this.
Each channel on the Internet has its own openvpn interface, both are up and users want to connect to the Internet and to a remote network on both channels.
Just like on the Internet.
We consider options for one router, and 3x - two border ones, each with its own Internet and vpn + balancer, which directs users to the selected channel.
Ideally, the solution is free)
Thanks in advance for any answers, and especially those supported by links;)

Answer 1

Several tasks:
For free, you need to google similar technologies.

Answer 2

The dumbest thing is to raise two vpns and if one falls then just transfer the routes to the second one with a script or some kind of smallpox.