It may be better to write a local command that keeps trying to create a master
ssh connection, until it gets redirected to a specific server. Then use slave ssh connections to get to the same server each time. It will be best if you can reliably tell which server you connected to without relying on anything transient; the command would just try until it verifies it got the right server. Otherwise you need to keep e.g. a tmux session in exactly one server and the command will recognize the server by it; if after (say) 20 tries no session has been found then assume each server has none.