Won a dog door at silent auction

In general, I don't have just one dog in the house. I'm usually babysitting somebody, or fostering somebody, or I'll have another dog sometime in the next year or two. Maybe I'm paranoid, or maybe I'm poop obsessed I want to know which dog it came out of, and when. Emma has had several brushes with blockage, in the past, and if I hadn't realized "gee, she hasn't pooped since yesterday", it might have meant surgery, for her. As it was, I got her to the vet and we dealt with the nasty things, and she passed them on her own. I just know that if *I* had a doggy door, and she had free access to outside, I wouldn't pay as much attention.

Of course, Teenie ate  her poop. It drove me nuts. I never knew if she'd pooped while I was gone, because she'd scarf it as soon as she could get her nasty little mouth on it. 

Cherokee's got 24/7 access to the yard. She basically just goes out to...eliminate. Once in a while she'll sunbathe for a bit, or go on possum-patrol at night, but otherwise, she's inside. The only times she's locked in are when there are actually possums around or when the gardeners come.

We have 6-foot secure privacy fencing all around the yard, with one padlocked gate. Nobody comes in unannounced, so it's just not an issue.

I have had dogs that are just guests......I have a kennel closed off just for that........this should be pretty easy.......maybe it isn't for some......sorry.......