Regarding Market Based Health Insurance, as the parent, do i check the box that asks if I shared the plan with another taxpayer? My son was recommended not to by you.

My wife and I share the health plan with my son. Son files his own taxes and is not a dependent.  TurboTax recommends he doesn't check the share box, but do my wife and I check the shared box?  We live in Washington.  If we do share, then I calculated our percentage is 80%, but what do we put in the three boxes that ask for the percentages?