Hi everyone,

Let me explain my scenario, I'll put the diagram below for better understanding. I have two cities connected.
City 1 has a link connected to a CCR1036-8G-2S+ (BGP)
City 1 has a BGP to City 2
City 2 has a proxy that can be turned into a link when requested (BGP as well)
City 2 has a CCR1072-1G-8S+
Both cities have each one another CCR that handles PPPoE clients.

I already have a failover set up between the cities, but what I need is that the traffic directed from and to some specific sites goes to the proxy. And I need that to happen in both cities.

Thanks in advance for any help.

You need to do this in firewall.

Mark packet, dst-ip's, src-ip's, url's or whatever your need i to havetrough another gateway.
Do something with this marked packets - like send trough gateway xxxx. Its a kind of same as bonding with mangle etc.

Read https://wiki.mikrotik.com/wiki/Manual:PCC