Marrying A Conjoined Twin

 In America, you can only legally marry 1 person at a time. But when someone marries someone who is a conjoined twin, don't they AUTOMATICALLY marry both of them? This is especially true if the conjoined twins share genital and reproductive systems. Abby Hensel just got married. But didn't her husband automatically in fact marry her twin Britney as well? After all, they have the same genital system! When he has sex with Abby, he is having sex with Britney, too. 

Want to get a threesome? Marry one of a conjoined twin and it is of necessity a threesome.