Can Previously Cooked Bones Be Used to Make Bone Sauce

We recently smoked ribs for a large gathering of friends.

I want to make some bone sauce to put on some newly planted trees that cows have developed a taste for.

Can Sepp's Bone Sauce be made using the left over bones that spent two hours in a smoker at 200 degrees and two hours in a roaster oven at 200 degrees?

I think so. Here is an article I wrote about it, wherein I used previously cooked bones

http://windward.org/2.0/notes/2014/2014andrew01.htm

Seemed to work just fine. Perhaps I got less bone sauce that I would from non-cooked bones? but I have no comparison. I've only ever used cooked bones.