I made 2 typed views
I get that you have 2 Views in the database, if they are related which is the case, you may map them to 2 Entities (ParentEntity & ChildEntity) and create the relation between them at design time.
Then you may use FetchEntityCollection() to get the collection of the ParentEntity, bind it to the first datagrid,
and then bind the second datagrid to the ChildEntity collection associated with the ParentEntity (field mapped on relation)
For Example:
((ParentEntity)ParentCollection[SelectedItem]).ChildCollection