You say you dont expect them to take sides....but I do --> HER side.
Exactly right. When it comes to BD, S and D, the old adage "blood is thicker than water" applies. Families will rally around blood relatives and shun the LBS NO MATTER WHAT. Your W could be the most insane, raving lunatic siren to ever cast a shadow on God's green earth and still her relatives will cluster around her in a defensive formation. This is NORMAL Tread. You shouldn't expect otherwise, no matter how great your previous relationship with your in-laws was.
