That makes more sense my comments were based on the original post.
Obviously they need to track down exactly what happened and when, for example on the face of it if your Sister was 12 when they left and she was born presumably in India and they were here 14 years that does not quite add up.
I assume you were born in the US when they were here.
There is no point petitioning your sister if she does not want to immigrate and it seems she was here for quite some time out of status, Mother is looking to move Sister here, well I agree with appleblossom.
Your Mother, yes she has served her 10 year bar for an overstay so the next question is if anything else is in her past that will require a waiver as you cannot file one.
https://www.cbp.gov/travel/international-visitors/i-94