The only way I can see Lothar and Leopold responding to each other is by fighting each other. That requires a declaration of war. As long as one player declares war publically or in a PM to me before Milan is taken, then it would be resolved in a PvP battle. As the rules stand right now, both sides have equal claim to assaulting Milan. It's regretable that this loophole in the rule exists, but it's not something that can be changed right now.