Well, it seems that after getting settled into their new home, she's back to nursing for her entire litter, and nobody is being left out. In hindsight, switching enclosures altogether was probably too risky, and simply removing the parents while changing the substrate surrounding the pups' nest would have been the safest bet. Something I won't do again until the pups are weened, but I'm glad that she's back to nurturing for all of her babies again.