Forms are parts of a graphical user interface (GUI) that show a (structured) value and allow the user to update it. Some forms express a choice between two or more (structured) values using radio buttons or check boxes. We show that explicitly modelling such a choice leads to a cleaner separation of logic and layout. This is done by extending the combinator library FunctionalForms with disjoint form combinators. To implement these, we have generalized the technique of compositional functional references which underlies the library.