Several points.
One, on the 'linked family members' - you are right, that there is exceedingly limited benefit to that feature in 2.11, which is among the reasons it was removed for v3 (or maybe generalized).
On the issue of sharing contacts between PHRs, this is one of the major new features of HealthFrame v3. In HealthFrame v3, you simple set a checkmark in the PHR saying it 'uses' the shared contacts, and then for each contact you want shared, you set a checkbox for that contact.
This is a very new feature, and will probably enjoy some 'growing pains', but I think it will give you at least 95% of what you are looking for.