All the advice I have to give is from my Pap, Pierre (sorry, no Sheltie... yet, but I hope this is okay). With him, I had to restrict his access to just the kitchen and I also kept up the paper training that my breeder had him on as a pup. Tons of patience outside seemed to just give in to his stubbornness. So if he went, I would reward him with a quick walk or even a long one time permitting. If he didn't, we went back inside after a few minutes. He really hates rain (and being in FL, it was a big obstacle to overcome) and prefers longer grass. Knowing where he likes to go helps a lot.
I'm wondering if she is paper trained or if she goes indiscriminately due to her upbringing. If she isn't paper trained, it might be a good start (and a relief when you have to leave home) to get her knowing that there are good places to go and not good places to go.
