And a destructive one.
A solution might be to make getting a "full" check dependent on points earned -- volunteer work, charity points, or points from adult children.
Some will have more children and they might be better parents. Being dependent on the kindness of adult children at some future time would be a positive incentive.
That´s undoubtly true. If we´d only reduce pensions for people without children! Or increase taxes for people without children (now that we´re switching to a more private pension system).