Can I book several rooms at the same hotel for one group in a single booking on my website?

Yes, in most cases you can. A hotel search on your portal will normally let you say how many rooms you need and who is staying in each one, including adults and children per room, and the prices that come back are built for that whole stay rather than for one room repeated.

How far you can take it depends on the supplier sitting behind those rates. Most hotel suppliers set a limit on how many rooms a single booking can hold, and once you go beyond it they stop treating it as an instant booking and expect a group enquiry instead, which usually means a quote by email and a different set of payment and cancellation terms. Some suppliers also require every room in one booking to be the same room type, so a party wanting a twin and a double together may come out as two separate bookings even though it is the same hotel and the same nights.

It is also worth knowing that rooms inside one booking can each carry their own rate and their own cancellation deadline. Depending on the supplier you may get one reference covering everything or a reference per room, and cancelling just one room out of several is not always allowed. Where it is not, the whole booking has to be cancelled and rebooked, which can mean losing a good rate, so it pays to check before you confirm anything to the customer.

The practical next step is to run a test multi room search on your own portal with your live suppliers, see how many rooms it will accept before it pushes you to a group request, and ask each supplier whether partial cancellation is possible so you know what you can promise a group.