Hi,
From what I can remember, NCrunch will always aggregate the ExclusivelyUses attribute values down through the inheritance structure. This means that once it's been declared on a base class, there isn't any way to then undeclare it on a descendant. Sorry, I can't think of any workaround here other than to change the design of the tests. It may be that you need to introduce a variation in your inheritance structure so that some of your integration tests have a different base class, allowing you to move the ExclusivelyUses declaration so it is more tightly targeted.