Does anyone have any experience with affirmative findings of family violence at the juvenile level. Can it be done? or Is it prohibited somewhere?

WHY do you need an affirmative finding of family violence?

If it is to enhance a family violence assault charge with a previous family violence - you can't do it.

To enhance to a felony requires a previous "conviction" (see PC 22.01(b)(2) ..."if it is shown ... that the defendant has been previously CONVICTED...", and a juvenile adjudication of delinquency isn't a "conviction." (see FC 51.13(a)..."an order of adjudication or disposition under this title is not a conviction of crime."

It can be done to enhance a Terroristic Threat from a Class B to an A, but other than that there wouldn't be any point as mentioned above.

My thinking was exactly that, enhancing to a felony on a previous family violence conviction or at least getting an affirmative finding so that the ehancement could be done for a subsequent adult charge. I had already decided it couldn't be done but was hoping someone smarter than me had figured out how to get around the adjudication vs. conviction distinction. While we're on the topic of enhancements, my reading of the law on DWI is the same, a DWI adjudication does not count for PC 49.09, right?

That's right, if the statute only says conviction you are out of luck on enhancement with juvenile adjudications.

That's why you can, in some situations, use a juvi prior for enhancment under 12.42 because under subsection(f)it allows for the use of "adjudications".