Burghs

I have a question about combining the free night certificates. I would like to stay four nights:

Night 1 - paid

Night 2 - paid

Night 3 - free (buy 2, get 1 cert)

Night 4 - free (free night cert)

Has anyone accomplished a booking like this? The buy 2, get 1 cert says it can't be combined with the free night cert. Not sure if that means they can't be used on the same reservation, or that you can't count the free night as one of the two nights you need to buy.

Any advice would be appreciated.