Forgive me if I've missed another thread with this info - you don't give the ages of your JRTs. How old is your female? I'm wondering if she's really peeing, or possibly instead becoming a bit incontinent? It's not uncommon for spayed females to become incontinent at some point in their lives - I'm wondering if this has happened to your girl. She may not be peeing, but leaking in her sleep. Have you actually seen her peeing? It's possible it's happening in her sleep and she doesn't even realize it - which would explain her not alerting you of her need to go outside. I'd recommend a vet visit to make sure there's not a UTI or anything else medical, but my bet is, your girl just can't make it thru the night. Have you tried getting up during the night and letting her out briefly every night? She may need one potty break mid-way thru the night (even tho she's not asking for one). Your vet can help you with age/spay related incontinence if that's what it turns out to be. For the time being, I'd try taking her out mid-way thru the night (sorry, but if you have to go, you have the ability to get up and go - she doesn't, and possibly isn't waking up to even realize that she needs to).
Someone else may have another suggestion or idea.