Populate Combox then Listbox by selection

Divinedar

You didn't add a revised file so instead I've given you an example which should help.

In the revised file attached, the first sheet has a new button saying "Demo ListBox selections". Click that and new form UserForm1 is shown then initialised as follows (with comments to help):

Private Sub UserForm_Initialize()

Dim Ct As Shape

' populate with all items
With Worksheets("Colt_Gov_Model_MK_IV_80")
   
   Set PrtsRng = .Range("B3:E" & .Cells(.Rows.Count, 2).End(xlUp).Row)
    Me.ListBox1.ColumnCount = 4
    Me.ListBox1.RowSource = .Name & "!" & PrtsRng.Address

End With

End Sub

REVISION 29 Jan 2023: only one list box is used in UserForm1

Note that the List box has the property Multiselect set to 2 - fmMultiSelectExtended (which means you can control click several distinct items and/or click one and shift click another to pick those and the ones between) .

The variable PrtsRng is declared at a module level so it can be used when the Submit button is clicked: 

Dim PrtsRng As Range

Private Sub Cb_Submit_Click()

Dim Picked As String

' loop through Listbox1
For x = 0 To ListBox1.ListCount - 1
    ' get Item name (e.g.) from array
    If ListBox1.Selected(x) = True Then
       Picked = Picked & PrtsRng.Cells(x + 1, 2).Value & vbCrLf
    End If
Next x

MsgBox "You picked:" & vbCrLf & vbCrLf & Picked
Unload Me


End Sub

Note that items in list boxes have the first item as index zero (0), the second as one (1), and so on. In the range, I just add a 1 to the counter x to get to the right item.

Hope this gives you a good idea of how to do what you want to do.