Hi shopaholic. Love your avatar!!!!!!
Great acting/tongue biting. I feel that letting those gals know that you do not believe in shunning anyone over conscience matters might alleviate some of their stress, without tipping your hand just yet.
Maybe in the future, after you quietly come clean to her, you can work out a plan with her to let the others know about the issues you have come up with (something like bigdreaux suggested). You might even use that as a springboard to let them know that you came to the same conclusions as your niece. That is, that you investigated those spurious claims and there was real substance to them-- and as a result you have to leave because your Bible-trained conscience won't let you stay with such deceitful teachers.
bebu