soft tortillas or crispy tacos, what are you trying to keep warm?for soft tortillas parchment between them will prevent sticking but do it in batches as the supply gets depleted on the buffet table add more to the bottom.crispy tacos will keep on a warming try dry heat

I've never had them stick together. Just wrap them in a tea towel. You can put them in a very low oven, towel & all for a few minutes in a casserole dish. By low oven, I mean under 200°.