I feel so lonely in my opinion that showing the parents' faces is unlikely to make a difference at this point, at least if their message so far has been correctly directed. It's clear from their words and actions how important this is to them, what exactly would be the course of action on their end or that of a lawyer's to bypass previously enacted legislation? Serious question.
And if it were to succeed, I can only imagine it being clickbait/TV revenue.. "The NEVER BEFORE SEEN parents speak! See it HERE FIRST!" and so forth.. it just sounds distracting and a bureaucratic waste at this point.
Especially since anybody who cares about William isn't sleeping or working very much while assisting in the search, or so I would imagine.
The most heartfelt pleas I've ever heard or seen probably came from Morgan Harrington's parents, and her killer was only caught years later because of another victim, Hannah Graham. The Harringtons, who remained MORE than fully visible in the media for years, described the look he gave them in court when they were finally able to face him as "evil." Which is what I think we're dealing with here, unfortunately.
I may just be seriously not understanding some media/legal/cryptic posting nuances, and I don't mean any offense by it.