I-130 and I-485 Help Please!!!

I really need your help please!

Ok my situation is kind of confusing but here it goes...

My mom became a LPR 3 years ago, and just recently she told me to file I-130 for my two little sisters (ages 15 and 17). My sisters entered the United States in 1996, when they were just babies, on an L2 Visa but they overstayed because the visa expired in 2006. USCIS sent an I-130 approval notice but they stated that my sisters were not eligible to file I-485 to adjust their status, and their case was sent to NVC. (Their priority date is Aug 2010)

Q1: Is the reason why they're ineligible because they overstayed?
Q2: And is there any way to still file I-485 since they were brought
over so young and have attended school here since kindergarten?

How did she get a green card? I am assuming marriage? Have your mom or dad been petitioned for work or any family petition before April 2001? They won't be able to adjust status unless they are grandfathered under 245i.

A1- Reason why they would be ineligible is because they are out of status. Adjustment of status is possible if you marry USC, have some sort of status, or grandfathered under 245i.
A2- Not that I know of. We are all in this situation. A lot of dreamers here have USC family members or legal parents, but can't adjust their status for this very reason.

Is the reason why they're ineligible because they overstayed?

They are ineligible because their visa has not become current. Check the visa bulletin (google it) each month until her priority date (august 2010) becomes "current". Your siblings are 2A category. Right now they are processing visas from 2008 and earlier than that, unless you are from Mexico. In that case it's 2005 and earlier.

Once the visa becomes current, they can send their i-485's, but they wont be able to do it before then. There's a slight possibility they might age out, but since the oldest is 17 and the visa is taking about 3 years, she will probably be able to barely make it... as long as things keep moving as rapidly as they are now.

I think dream-hope is right. Ignore my previous post, since I misinterpreted your post. I thought your mom filed I-130 for them even though they aren't eligible to adjust status here in the U.S. If they are eligible to adjust status, they can file as soon as their priority date becomes current.