Cascading combo boxes

Hello there,

I've used the standard microsoft instructions to use the Northwind database and created two syncrhonised combo boxes.

However, my problem is that I can't find any further information on how to link a third combo box.

The principle I'm working from is:

combo box one - staff contact: this filters the available orgs in combo 2.

combo box two - organisation: this filters contact details specific to the organisation selected.

combo box three - contact details.

I've worked out combo one and two. Any advice on the third? A step by step process would be great.