<ExtensionAttribute()>
Public Overloads Shared Function Union(Of TSource)( _
   ByVal source1 As IEntityQuery(Of TSource), _
   ByVal source2 As IEnumerable(Of TSource) _
) As IEntityQuery(Of TSource)

Dim source1 As IEntityQuery(Of TSource)
Dim source2 As IEnumerable(Of TSource)
Dim value As IEntityQuery(Of TSource)
 
value = EntityQueryExtensions.Union(Of TSource)(source1, source2)

[ExtensionAttribute()]
public static IEntityQuery<TSource> Union<TSource>( 
   IEntityQuery<TSource> source1,
   IEnumerable<TSource> source2
)

[ExtensionAttribute()]
public:
static IEntityQuery<TSource^>^ Uniongeneric<typename TSource>
( 
   IEntityQuery<TSource^>^ source1,
   IEnumerable<TSource^>^ source2
) 

var mgr1 = new DomainModelEntityManager();

var query1 = mgr1.Customers.Where(c => c.Country == "UK");
var query2 = mgr1.Customers.Where(c => c.Region == "CA");

var combinedQuery = query1.Union(query2);
var list = combinedQuery.Execute();