Adding free accommodation nights

Hello,

Has anyone found a workaround regarding applying free accommodation nights as a discount? Almost all of the hotels we work with offer free hotel nights such as 8th, 9th, 10th night free and as far as I can see, the only workaround is to make a manual adjustment after the guest has made an enquiry.  Ideally we would want the discounts reflected in the guest's quote so they can see the final price. We also have blackout dates such as Christmas and New Year and would need to apply the free night(s) to the lowest rates (if the dates straddle two seasons) as this is how our suppliers bill us.

Any ideas?

Thanks in advance,

Tom