I have a project where all the VLOOKUP lists and tables I use for
calculations and such are in a single sheet named LISTS that is hidden
in the templates workbooks my clients use.

Any ideas of how to go about creating and sending them a update
routine or form with a button that would automatically replace their
existing password locked and hidden LISTS worksheet with a new one?

Some of the data in the LISTS I prefer that they not see though it is
used in their calculations. Periodically I need to update these
lists. Currently I have to get their templates, update the sheet and
return their templates. Big pain.

I had considered creating an UPDATE worksheet form that maybe they
could place in the same folder as their template and then button "run"
code that would copy the new LISTS from the hidden and locked UPDATE
worksheet in my update to their template.

Thanks for your suggestions,
Dennis