DataForm Add/Remove for EntitySet and EntityCollection
With our initial V1.0 release, many of you found that a DataForm bound to an EntitySet or an EntityCollection did not support the Add or Remove buttons. This was a difficult cut to make in V1.0, so I’m pleased to announce that with V1.0 SP1, this is now supported. Silverlight 4 introduced the ICollectionViewFactory interface, with support integrated into DataGrid and DataForm, and both EntitySet and EntityCollection now implement that interface to allow the Add/Remove features to light up.
Be sure to keep an eye on Kyle McClellan’s blog for more information on this feature. You’ll hear us refer to it as ICollectionViewFactory or ICVF.
This brings in the CollectionView support added in WCF Ria Services SP1
Qutoe from : https://jeffhandley.com/2011-03-10/riaservicesv1sp1rtm