Take her to the vet first, make sure it is nothing medical, especially as this is such a new occurrence, okay? Some females get spay-related incontinence, it's not that common, but also not unheard of, make notes of when it happens and the circumstances, okay? Are you making sure you still give River some one-on-one time, so you know it isn't a jealousy thing? Especially as the new pup is allowed to sleep in your bed, you might want to reconsider that, because it could be River is trying to "mark" it is hers, because the pup peed there ... and gets to sleep there, and she doesn't. Why are you allowing the pup in the bed, when River never did? that's sending mixed signals to her, for sure.