In an odd way, your constitutional amendment (b) would outlaw marriage altogether.
When you have an inalienable right to something, you can't bargain that right away through contract.[1] An inalienable right to define who is family would make it impossible for anyone to enter a "contract" for an exclusive relationship (which alienates your right to marry others you want to have in your family).
You couldn't get married (at least as that term is used now) any more than you can enter a contract to become a slave.
When you have an inalienable right to something, you can't bargain that right away through contract.[1] An inalienable right to define who is family would make it impossible for anyone to enter a "contract" for an exclusive relationship (which alienates your right to marry others you want to have in your family).
You couldn't get married (at least as that term is used now) any more than you can enter a contract to become a slave.
[1] http://legal-dictionary.thefreedictionary.com/Inalienable+ri...