This would be to:
Tell each other what we actually let them wear and watch and buy and do, instead of hearing all the time "ALL my friends do it!" and secretly wondering if we're really the only parent on earth who makes their child miserable.
Share thoughts on how not to go mad every time we hear "yeah sure I'll do it in a minute" and then see our dear teen disappear for a few hours... or urgently need the bathroom... or suddenly remember a missed homework... or feel sick...
To make a list of all the things we need to change so they're happy, all the things they know better than us... starting by who we are, what we eat, where we live, what time we wake up, what we watch, what music we like, how we drive, the choices we make, what we cook ... I'm sure I left out loads.
And much more (suggestions welcome)
I think such a Union would be great 
AIBU?