New rescue dog resource guarding from older dog

Hi!! So we've had our 4 year old Samoyed Gracie since she was a puppy, she's so lovely, has never resource guarded or anything, and we've had foster situations and she's never minded other dogs being in her space, eating her food, etc. We just got our 7 month old Samoyed Lulu from a rescue program and I noticed her display signs of resource guarding, not over food, but over toys. She's been making a pile on her dog bed of all the toys gracie touches and growls and snaps at gracie if she gets near it. gracie doesn't react, just stretches and walks away.

i work in animal rescue and just started studying my minor in animal behaviour so im feeling a little useless since i haven't covered this topic yet. sure i've covered food guarding from humans but ive never covered toy guarding from older dog. i know lulu isn't showing aggression and probably overstimulation (lulu peed right after in the house), but we definitely caught it early and i'd love some support on what to do.