RE: Passing a date from a form to a form part where the datasets are not the same.

You have many ways. For example, if the value is in a datasource, you can pass to the other form and read it from there (what kind of datasource is used by the target for is irrelevant). If you have it in a variable only, you can save it to an object and pass it to the other form through Args.parmObject(). Or the target form can get a reference to the caller form (element.args().caller()) and call its method to get the value. And so on.