selecting sheets
 

Can anyone recommend some syntax to do the following. I
have created a user form containing a multi-select list
box. This list box is populated by names of specific
worksheets in my Excel file (but not all of them).
I've added an option button to the user form which is
intended to allow the user to select ALL of these sheets
at once in place of the multi select list box.
What is the best way to code this, without using explicit
sheet names, remembering that these sheets do not
represent all the sheets in the workbook.
Can anyone help?
Many thanks
Jacqui