Sarma. I have eaten stuffed grape leaves before. It's been a long time ago, but I think it was a rice and ground meat mixture. Do you ever use meat in your recipe? I can get ground Lamb at the local grocery store.
We have wild grape vines here. There are a couple of varieties, one leaf is deeply lobed and would probably be a rolled grape leaf failure. The other one is a nice full leaf and would be suitable for rolling and stuffing.
So.... sprinkle the sumac on after cooking. I can see a lot of possibilities with this.
I can send you a box of roots in the fall if you'd like. I would have already sent you some, but in this heat, they would arrive as composted, decomposed goo. That would give you a sumac forest by next spring. LOL