Clarification needed on buying the maximum number points

I am currently short on points for a stay at a Hilton. I am already transferring my VS miles into my Hhonors Account. I am also thinking about purchasing 40,000 points under the current promotion at 0.8 cent per point. After that, I still need 7000 points to get the whole stay covered.

When I am playing around with the Hilton’s reservation page, it is allowing me to make the reservation by buying all 47,000 points that I need at 2 cents per point. However, that is over the maximum of 40,000 points that one is allowed to purchase. How is that allowed?

So, should I purchase my 40,000 points at the lower rate first? Then, I will make the reservation and hope the website still allows me to purchase the reminder of the 7000 points? Or, will the website be smart enough to figure out that I have already purchase the maximum points?

Thanks