Ask your MIL what berries are native to her country and in season. As you know, cranberries are really TART when whole and fresh. But when dried what is left is the natural sugar that all berries have. Thus they become sweet. Is there a military base near where you are? If so, ask a military person if they can help you. Ocean Spray ships frozen and dried cranberries overseas to our military bases so our men in uniform can have a taste of home.
You could use raisins. But that is a last resort. Good luck.