I've never been able to do this. Seems like it's "choose one of these guys or promote someone."
I think the idea is that at any given time you can only choose one of 3 new hires. If you choose to hire no one you get a promotion point. Those you can save for later.
If there is no one good, you can just not hire someone until the next group of applicants is knocking at your door.
I think...