Oh, I agree -- I believe that the persons whose parents are being unfair need to set the boundary, not the spouse.
But on the other hand of thinking, what if the spouse can't/won't set a boundary? Should the spouse just take it....or should they speak up for themselves?
That's something I struggled with (and admittedly still do).
M:32,H 32 T:10, M5 BD/H Move Out: 9/2014 - extreme anger H Mental Illness Diagnosis: 4/15 Served D Papers: 10/15 Divorced: 11/15