months with a 5th weekend

Annplus1

Our custody order states that I get the 1st and 3rd weekend of the month, and EX gets the 2nd and 4th weekends. But what happens on the months that there is a 5th weekend? How do you handle that?

My girl is now 2 weeks old, and already EX is dodging dates and giving back time. But he is trying to use everything he can to make himself the victim. I need to be proactive about that date, and do it fairly. Which is why I am looking for what you guys are doing already. 

Thanks!