Cascading Combobox - unlimited range in frst box

Please help me find a solution to this problem. I have searched SEVERAL forums, and couldn’t find anything that helps in this case

I must use a Userform, so data validation does not apply to this problem.

I have 5 comboboxes.

Combobox 2-5 is dependent on the choice made in Combobox 1.

Now, the problem lies in this:

Combobox 1 has a list that continuously grows and thus the normal cascade code like the one below does not really work because I can’t just hardcode every single choice for Combobox1.

   If ComboBox1 = "XXXX" Then
    	ComboBox2.AddItem "XXXX1"    
ComboBox2.AddItem "XXXX2"   
ComboBox2.AddItem "XXXX3"

Also, Combobox 1 normally has choices that are made of several words and not just one.

Basically, imagine having a mail-merge document made of a spreadsheet with contacts from hundreds of companies. In one column the company name is repeated many times as there are several contacts in each company.

The Userform uses this sheet as its source.

Combobox 1 could determines the Company
Combobox 2 could determine which Contacts there are in this company
Combobox 3-5 could determine the region etc. depending on the choices made above.

Any solution would be greatly appreciated.