I am curious if they didn't know she was pregnant when they adopted her out, who came to the conclusion that it would be a dobe that was the father?
If this breeding only took place a short time ago, the vet can abort the litter and spay her.
ALL of our rescue programs and shelters here either have the pet spayed or neutered before adoption or require proof of a scheduled apointment and a paid in full receipt before they will let the dog/cat leave the shelter. I have never heard of a shelter that adopts pets who have not been fixed.
Take her to the vet and see if he can take care of this would be the best bet.
Best of luck!
Friends will step in when the rest of the world steps out.