Over-booking resources in Outlook

[Cristtos]

We have an issue with people booking resources (by invite) for a few days
(whole day booking).
When you do block day booking (by invite) it comes by default with the
resources set as free for the day!
Thus the system will accept subsequent over-bookings :-(

When you book on a block of time within one day it comes by default with the
time as busy!

I have tried educating people but it does not appear to work

Is there a hack that I can use to set the status to come by default as busy
even for the full day events?

Thanks

Cris