To avoid conflict, you can use Google Calendar. Google Calendar will allow you to update and have the other person(s) you share the calendar with to receive those changes immediately. 2Houses is another option you can use to organize yourselves. 2Houses makes it easy to organize a custody schedule, manage kids' expenses, upload photos and notes, and exchange all necessary information. Such information as medical notes and school details. It also comes with a messaging service and mediator access via the web and mobile devices.