Create "Master" Listbox From Choices In Another Listbox

I have two listboxes on a userform. One is the "choice" listbox, the other is the "master" listbox. Each item selected is a billing object on a sales invoice.
problem: The master list works fine when the item is selected in the choice list. But when it is deselected, how can you REMOVE it from the master list? question: How can I add a text box automatically to the userform to allow the user to enter quantity info?

For I = 0 To CodeList.ListCount - 1
If CodeList.Selected(I) = True Then
obj = CodeList.Column(0, I)
p = 6
test = 0

Do While test = 0 And p <= 25
If sheetsales. Range("C" & p) = obj Then
test = 1
Else
test = 0
End If
p = p + 1
Loop
If test = 0 Then.........................