Membership with parent and child function

Hi there.

Having trouble finding a plugin that can solve my membership needs.

I have this volunteer club for kids where I need a membership or signup system that enables me to have the parents register with informations about herself or himself.
That includes informations that should not be shown on any public profile page – but only to administrator/staff members. (Like social security number)

At the same time, I need that parent to be able to signup one or more kids to the club. The kids account should be linked to the parents account so that we (staff) can see the association. (In case of emergencies)

And at the same time the parent should be able to signup for volunteer shifts at the club on specific dates with a maximum numbers of volunteers per shift.

Does anyone now of any plugin or combination of plugins that could cover my needs?

Thanks for helping.
Dan Hansen