It sounds like you might need to consider revisiting and amending your parenting agreement to better fit everyone’s schedule. At one time, you could have an agreement called a “first right of refusal.” This was a common provision, which reads that if one parent who has the kids is gone for more than four hours, s/he will call the other parent and offer them the “right” to parent the kids before anyone else. ?Unfortunately, this made people fight more often than it solved any problems and it is disfavored by the courts. Co-parenting requires constant changes, especially if a work schedule changes. ?Also, if it ?is just a temporary time change, ?it often might be a good idea to allow the grandmother and the kids to spend this time together. ?Did you encourage this relationship when you were still married? If so, why not continue it now? Remember, you might be in the same situation some day and you will want understanding and consideration from your partner at that time.