XLA and strong typing
 

Hi
I have a workbook with several sheets. The flow thru
the "application" is staitc. The VBA changes a lot and
therefor I want to have most of the code in an XLA so I do
not have to change all the users Workbooks. The problem is
that I am found of stong typing and I have not managed to
incoperate strong typing and XLA. For example:
In my Workbook, which have a reference to the XLA, I have
a sheet called Sheet1 with several comboboxes. I want to
pass Sheet1 to a XLA function which popultes the boxes,
but I can not do that because the XLA do not know the type
Sheet1...! I would like to declare Sheet1 in a third place
which both my Workbook and XLA know. Probably I have
missed something simple but can this be done in some way?
Best regards
/Niklas