Carolyn adopts Martin after St Petersburg (without asking first, of course). It's a very sensible choice - she's not getting any younger and Arthur is not getting any smarter, so it's only logical to get herself a son who will be at least half-competent at managing the company when she's gone. Besides, this way she can keep not paying Martin without feeling bad about it - instead she takes him into her house, feeds him, washes his clothes and generally unleashes all the motherly urges she's been trying to keep inside (deep, deep inside. Very deep inside.) on poor, unsuspecting Martin.