Legal exposure for children in gun owning households

From today's Globe:

A 10-year-old boy is facing gun-related charges after he allegedly fired his father’s rifle into a neighbor’s Halifax home Tuesday night, police said.... Halifax police Sergeant Ted Broderick said the son will face charges of discharging a firearm within 500 feet of a building, possession of a firearm without proper license, possession of ammunition without a proper license, and destruction of property.

Enough has been said about how ridiculous it is to charge the child with a crime here.  Most licensed firearms instructors in Massachusetts don't understand the basics of the state's convoluted ammunition and gun laws, let alone a ten year old, so it's pretty far-fetched that the boy intended to commit a crime.

Could the boy have really possessed ammunition that was bought by the father and stored in the father's home?  This is worrisome - children cannot hold a license to carry, and if they live in a household where an adult legally possesses gun and ammo, the children may have legal exposure.  What if a dad leaves his 17-year old at home with properly stored ammo?  Can the minor be charged with possession without a license?  What about when my unlicensed wife is at home without me, and my guns are stored in the closet with trigger locks in accordance with MGL?  Is she in possession? 

I believe she would be committing a felony by the letter of the law.  In practice it doesn't keep me up at night, because we're not exactly on the police radar.  But it does show how Massachusetts' bizarre gun laws can trap honest people who have done nothing wrong. 

In the Halifax case, I suspect the DA is trumping up a charge for the sole purpose of making this boy a prohibited person, "getting something on his record," to prevent him from owning a gun when he becomes an adult.  I don't know the local politics in that town, but I wouldn't be surprised if there was pressure from some liberal mayor or city council wanting to appear "tough on guns."