I've been making chicken soup for decades, but today I'm in a little bind. I have two large enough chicken thighs with bone in. How much water and broth should I use?
While I agree that the question is unclear, there is perhaps a clear answer to this from either of the directions that I can see.
If you are intending on making the thighs into stock -, add your other ingredients (veges, herbs etc), if any and cover with water.
If making soup from these and adding stock + water to cook the thighs so that they are eaten as part of the dish as a whole - then again, cover them with liquid. How much of each component you use is up to you, but I would suggest all liquid stock for this scenario. If you have a more concentrated stock, then dilute to taste with water.