Extending Combo Box capacity with an array from a range?

I am attempting to build my own Data form in order to emulate an Excel Data form - since Excel's is not accessible for modification.

Making a choice in Combo Box 1 will return a list ( with the duplicates removed ) and thereby present the user with a list of choices in Combo Box 2.
When a choice is made in Combo Box 2, it will populate 8 text boxes for viewing or editing.

As far as I know, a combo box can have only 10 columns as add-items.
I thought that by passing the 12 column range ( when finished, will be approximately 700 rows ) into an array, it might be possible to increase the amount of Text Boxes I could place on my form, from 8 to 10.

This is beyond my skills set and I was hoping for some input on if and how this might be achieved, and if a scroll bar could be used in the same manner as an Access data picker; in this case, to increment through that selected list.

I've attached the file to help illustrate my points.
Thanks!