Question: Can you use the steam from boiling one thing to cook something else?
E.g. Boiling potatoes and steam broccoli in the same pot at the same time.
Thank you!

Answer: 
Yes, if you have the right pot, namely one that has a steamer insert that is well above the bottom of the pot, [or even stacks](https://www.walmart.com/ip/3-Tier-Premium-Stainless-Steel-Steamer-Set-9-Inch-Diameter-Cookware-Pot-Saucepot-Multi-layer-Boiler-For-Cooking-Soup-Steaming-Food-Steam-With-Tempere/864298554).

In fact, in several cuisines this is the standard way of getting several ingredients ready at once. For example, it's common to steam couscous in the steam from the Moroccan stew cooking below, using [a stacking pot called a couscousiere](https://www.thespruceeats.com/how-to-use-a-couscoussier-2394753).

Just make sure that the food in the steamer will take less time to steam than the food below takes to boil.
I'd say yes, but.... Yes, but the steaming food may release a lot of colors and flavors into the water below, so be aware of this. I for one, would love broccoli rice, or beet potatoes, but not everyone might.