I have a user form with a two combo boxes wheras one reads 'Main Category' and the other 'Sub Category'.

To make it simple here is a little preview:

Main Category: Plumbing
Sub Category: Showers, Toilets, Doors

Main Category: Electricity
Sub Category: Switches, Receptacles, Wires

The Code of my Main Category is as follows and works fine:

Private Sub UserForm_Initialize()
  Dim rngColor As Range
  Dim ws As Worksheet
  Set ws = Worksheets("Categories")
  For Each rngColor In ws.Range("MainCategories")
    Me.cbomaincategory.AddItem rngColor.Value
  Next rngColor
End Sub
Is it possible tough to create a code that is dynamic (adding a new item will automatically show up in user form) and dependent (sub category is dependent on value of main category)?

*I tried Excel Data Validation, but it seems not to comply when using user forms...