Reheating grilled hamburger patties We grilled a bunch of meats for a large party. Now I have leftover hamburgers, hotdogs, and bratwursts. Note these are still “bare” meat items, not assembled hamburgers etc.

What’s the best way to re-heat a hamburger patty and still have it taste good, not overcooked, and not separated from its juices?

Any advice for the other items would be good too, especially if they can be done together. But the ground beef patty has always been less than successful for me in warming the leftovers.
If you have a pre-cooked burger patty, I'd suggest heating it in a frying pan / skillet over a high heat, add a splash of water and then cover with a small heat-proof bowl (a cloche), or a lid on your pan. The water will steam the burger back into life, adding moisture and trapping the heat to more thoroughly warm it through. 

I also use this technique when initially cooking burgers if you're not grilling outside - does wonders to melt any cheese you lay over the top of the patty in the pan!