Apply macro between tabs

Good Day,

I am really new to the world of macros and this is my first post, so my apologies if my question makes no or little sense. I will try my best to be as concise as possible.

I have a worksheet that I am always adding sheets to by duplicating an already existing tab. The tab ,"Current Invoice", is nested between sheets called "first" and "last". All duplicate sheets will also be nested between the "First" and "Last" tabs. What I would like to do is have a macro that affects all tabs between the "First" and "Last" only, even when the bookend tabs are hidden.

This is what I've started with.

HTML Code: 

Any advise you can offer would be great. Thanks.

Regards-
Kiki

Maybe this:

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Still not sure I follow entirely but perhaps:

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