The Man marries one sister and she marries her sister
Since the man is married to only one woman, it is legal. A sister wedding a sister might be incesteous but there is thus no bigamy
There’s still bigamy, being committed by the sister who’s married both to her sister and to the guy.
That’s still bigamy because the one sister is married to two people- but if she self identifies as a poodle, then the other two would only be charged with bestiality- but hey- who are we to judge? And at least there will be no icky bigamy going on- Perhaps one woman could self-identify as a deceased person- that way it would only be necrophilia- (and as in the days of Noah- everyone did what was right in their own eyes)
Nor might that be construed as ‘incestuous’, as the sisters cannot ‘formally’ fornicate/reproduce. More stigma opposition than biological.
I mean, if we’re going to take bizzaro logic to its bizarro conclusion...