Copy mailing list to all users in DB, create custom plugin?

I was hoping to get some advice the best way to do this & how complicated do you think it would be if I was to hire someone to create a plugin for me?

I have mailing list plugin where you create a mailing list and it generates the code for to use to add the opt in form to any of your pages.

So when you add a new list it adds a row to the table in your database such as wp_119_mailing_list and contains the unique id with the name of the list.

Since this multisite I would like add that same row to the same table that already exists for all my other users in the database.

Would that be easy for someone to make that knows sql?

thanks!!
-George