I reckon if you've already got 5 you'll hardly notice another one. Besides, it sounds to me as if you've already decided to adopt her but you're hoping someone might give you a good reason not to.
We have 4 cats and two dogs. My husband is the one that likes the cats though. He's going to be the crazy old cat man if he outlives me. I can see it now. lol
If the cat has kittens, maybe you'll be able to find homes for them. Do people just stick a sign out front that says 'free kittens' over there? That's what we do here. Usually it's not too hard to find homes for them.