If the older dog is painfully shy, to the point of not settling down to take care of late night outing, did she also skip eating dinner?
If she didn't really eat or drink much, then you're probably fine until morning. Dogs are very much "in with the new, out with the old". My dogs go out every few hours, but they don't really have to. Unless they've recently eaten, or after the 7-8 hour overnight time.
Yes, she's staying my brother's and SIL's laundry room (she belongs to SIL's parents) with a bowl of food and water right next to her crate. She doesn't seem to eat much, though. She's in the laundry room because that way it can be shut off while she's eating, or the other one will come in and scarf down all of her food.
I went back in just a bit ago, though, and
this time she was willing to go out...and, after relieving herself, apparently wanted to spend the rest of the night sniffing every square inch of the yard. Dear dog, you had all
day to do that....
The idea of standing around waiting for another creature to defecate just boggles my mind-- especially if you have to pick up the, err, product and dispose of it afterward. Guess I'm really not cut out to be a dog-owner or a mom.