From T&C: Stays that are booked via third party websites other than the websites of Hilton HHonors airline partners are not Eligible Stays irrespective of rate paid, for the purpose of earning points, miles or stay credit toward VIP tier status.

This statement is a "trick", I have booked at the airline partner site and had the points taken back during an audit 8 months later! No amount of documentation would change their mind, don't fall for it.