I come from a family that regularly made bone broth.
Regardless of how many bones you start out, if you cover the bones with water and a bit, you'll make a good broth.
Beef bones can be browned in the oven first, and this adds colour as well as a bit of flavour.
If you ever make it and think it tastes too strong (I never do, and it sure isn't gross!) just add some water.
Hope that helps.
Female, age 51, 5' 9"
SW - 183 (Jan 22, 2012), CW - 159, GW - healthy.
Met my 2012 goals by losing 24 pounds.
2013 goals are to get fit and strong!