I have new comers tell me that they saw a friend stack 4 ovens high, and it was so neat. For show, yes it is, but for practicality, not so good. To keep them in balance, you must start with a large one and work up to the smallest. That makes your bottom charcoal count off, OOO, BURN, and to check the bottom one, you must remove the top three. To much work for me. I don't mined removing the lid a time or too, for spectators to see what I am cooking. To much work it they are stacked. Stacking dose save about 15-20 charcoals, but charcoals are cheep. You have fun cooking any way it is fun for you. Thats what dutch oven cooking is all about.
Good friends, Good food, good fun.