Sorry, I can't seem to find the answer in the book, but are there rules for holding an action?
Can my character move, wait, and then attack the first baddie that comes near?
That could be a good idea if you want to hold the door. Other possible actions is Taunt or Intimidate to make the enemy Distracted or Vulnerable. With Khel out on the woodworks (though I am willing to let him retcon and stay on hold until someone is in view without having to reroll), it could also be an idea to hold the stairs.
I forgot to mention it in the flavor text, but these creatures aren't wielding ranseaurs and instead is relying on natural weapons. So they won't have the same reach.