Index formula to pull unique names only from a column

I think I may just be over thinking this, but im to the point where id rather ask instead fo assume.

I was playing with the define names in the formula tab to preload combo boxes (have that part figured out)

But I was running into issues with figuring out how to get defines names to show unique values only.

I was trying to use and index but im just messing it up... any ideas from the wiser forum users?

Attached a spread sheet with a name list similar to what im trying to adjust.

In B2

=IFERROR(INDEX($A$2:$A$700,MATCH(0,INDEX(COUNTIF($B$1:B1,$A$2:$A$700),0,0),0)),"")

Copy down

List of unique names

Would I be able to place this equation into the define name feature to make the list?

Im trying to figure out a way to make the preload for multiple comboboxes in a user form faster.

I had been having issues finding a way to do so