@Vampiress007 I mean you can have them have a sit down to air out all the bs. It'll get messy but they all are messy. Divorce but "married" on paper. Han and would fight about it, but in the end when they see that it's actually better this way instead sneaking around.
Money issues and raising the kids will araise but that would be because somebody (Seungmin) would be bitchy about it.
ChangBin would act like a moody teenager because teenager.
I.N would be happy for Lee since she has seen how her sister been treated, but would absolutely gag when Lee and Han get lovey-dovey. The babies could be effected by it but a happy parent makes happy child/ren
Now the grandparents might not understand the whole switch thing since they're old-school but again when they see how everything is going good they'll probably be on board.
But if you really wanna be messy, have both wives fall in love with female friends and get divorce and live happily ever after.