OP, summer is Dad's time so in reality, any summer activities should be discussed with Dad and kids -- and then you. Now, it's the other way around and then some -- it's discussed between kids and you, plans set, hopes high, then Dad is informed what shall be. That would be like Dad making plans with kids during school year when it's on your time and *telling* you how things are going to be. See how that's backwards? You need to have kids call dad and speak directly to him about things they are interested in doing over the summer and let them work it out and then Dad can talk to you about plans they've made and see if they're OK with you, too. Until that happens (Dad talks to you about proposed plans), you need to stay out of it with the kids, not buy into their feelings or anything of that sort, it's between them and Dad. Let Dad be in the driver's seat. It's his time with the kids and is only right.