Advantages and Disadvantages of Referencing An Add-In Workbook

Let me give you some background information first. I have a workbook (Quote
Generator v3.xls) that references an add-in workbook (QG Add-In v3.xla).
The Add-in workbook contains macros to manipulate data in the Quote workbook.
So when the Quote workbook is opened the Add-In workbook is opened hidden
from the user. I should also note that both of these files saved on a
server, thus several sales people use them.

Here is my question. When a user opens a Quote workbook the Add-In is
automatically opened. If I need to make updates to the Add-In, because of a
"bug" that I fixed, I currently have to tell the entire sales team to close
out Excel completely, do the update, then tell them its ok to continue. This
is not desireable. Is there a way to overwrite the Add-In workbook even if
someone may be using it? If not, anyone have any other ideas?

I was thinking of removing the reference to the Add-In, putting code in the
Quote workbooks Open Event to open the Add-In workbook as Read Only, and then
set the reference to the add-in. Does anyone know of any disadvantages of
doing it this way before I spend time writing code on this?

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Cheers,
Ryan