It is common for leagues to play games with each other, particularly for older teams and competitive teams.
If your league is hosting games that are scheduled by another league (such as a traveling league), and that league is a MySoccerLeague.com customer, then you can use MySoccerLeague.com to assign referees to those games. This is true whether or not your league is a MySoccerLeague.com customer. (First the scheduling league needs to enter your league as an affiliate, and then your league administrator needs to add you as the Referee Coordinator.)
When you click on View All Referee Assignments only the games that are scheduled on your fields will be displayed and available to assign referees.
If the scheduling league is not a MySoccerLeague.com customer, and your league is, then someone from your league needs to add the games into MySoccerLeague.com (See The Traveling Games Division). Once those games are added, they can viewed by clicking on Traveling Games on the View League Page. They will also be displayed on the All Referee Assignments page so that referees can be assigned.