Combining Regio-Ticket Bayern with "Grossraum" tickets?

If you stay in Middle-Franconia (Nuremberg and surrounding) for more than a week and want to travel withing that region with public transport, probably the cheapest option is the VGN-Gesamtraum 9-Uhr 31-Tage Ticket. It's valid for a month, and you can use it in work days from 9 hour, and in free days without limitation.

However, when you already have that ticket, and you want to travel with train somewhere outer "Gesamtraum" or "Grossraum", for example to Regensburg, can you combine that with Region-Ticket Bayern? It seems to be the cheapest option, because it allows 50km back and 50km forth travel, and costs 11,50 Euro, 2 times less that Bayern-Ticket.

However, I have found no information if it's possible to combine them with "Grossraum" tickets. For example, if I take the train from Nuremberg to Regensburg, the route until Parsberg is covered by the "Grossraum" ticket I already have, and the route from Parsberg to Regensburg could be covered by Region-Ticket Bayern. The only problem is, it's the same train and I don't have a ticket for the full route.

I've failed to find any information about that in internet...