I have a form in which I felt that tabs would be beneficial to divide up the long data entry into smaller related groups. However, after I divided up the information into 5 groups, some were still too long so I decided to subdivide the groups and tried to nest tabs within tabs but the result was that the "inner" tabs were just a layer over top of the outer tabs. We have an Access application at work (created by an outside contractor) where there are nested tabs so I know that somehow, it is possible to create this type of system but my (somewhat newbie) attempts failed.
The so called nested Tabs is actually another Tab Control overlayed onto the main Tab Control with its' Visible property set to False thus making it...invisible .
When a specific page is accessed within the Main Tab control the visible property of the nested hidden tab control becomes visible. If another page is selected from the Main Tab control, then the nested tab control becomes invisible again.
To demonstrate this, I have created a small sample (attached). As you can quickly see...things can get quite difficult to deal with when all the tab controls are set in order.