Dim wkbkdestination As Workbook
Dim destsheet As Worksheet
For Each ThisWorkSheet In wkbkorigin.Worksheets
\'this throws subscript out of range if there is not
As checking for members of a collection is a general problem, here is an abstracted version of Tim's answer:
Function Contains(objCollection As Object, strName as String) As Boolean
Dim o as Object
On Error Resume Next
set o = objCollection(strName)
Contains = (Err.Number = 0)
Err.Clear
End Function
This function can be used with any collection like object (Shapes, Range, Names, Workbooks, etc.).
To check for the existence of a sheet, use If Contains(Sheets, "SheetName") ...