It's practically impossible to apply constrains onto an item in an array. Most users get around the problem by nesting in another family and using the array command on the nested family. This is a ridiculous work around and shouldn't be necessary. In fact, the entire Revit constraining architecture has loads of problems. Autodesk Inventor's constraining system is far superior and it would benefit Revit significantly if constraints had a larger capability or recognizing free points of movement like Inventor does.
