I'd suggest blocking out the dates on all your one bedroom listings, then create a new listing for the whole place. The guest can then book the whole place as one with the rate you're looking to book it. This is also effective in the future in case you have another situation where you may need to rent out the whole place again.
If it were me, since I like to do things easily, I'd block out the dates on all listings except one. Then in the one listing send a special offer for the duration and grand total that you'll be renting it out for, just make a clear and concise Airbnb message that states that all your listings will be reserved for this person and his/her guests, or if it's specific bedrooms, I'd list them one by one with the link like so:
Bedroom 1: "link"
Bedroom 2: "link"
That way, you have all communications under one bedroom. If anything happens and Airbnb has to do any investigative research, the information is under one listing. I'd also suggest upping your security deposit and factoring in a cleaning fee to reflect that the whole place is being used and any incidentals to each and every bedroom.
Otherwise, you're really unable to have an all-in-one booking for all your listings. Each listing will have to be booked individually.
