Can I petition for my mother and sister for a green card ?

Hi, you can petition for mother green card via an adjustment of status because she is your immediate relative and her visa overstay can be forgiven. You may petition for your sister's green card but it will take long time and her visa overstay may not be forgiven. Consult with an Immigration attorney to determine eligibility and explorer the best course of actions.

As you a U.S. citizen, you can sponsor your mother while she is here in the U.S. even on an expired visa. Your sister's situation is more complicated. For one thing, sponsoring your sister will take at least 11 years. Further, your sister, if out of status, cannot adjust her status here in the U.S. and will be subject to bars to re-entry of she leaves the U.S. Schedule a consultation with an immigration attorney to thoroughly review the situation and explain your options.

As a U.S. citizen, you can file the FORM I-130 on behalf of your mother. If your mother entered the U.S. lawfully, she will then be able to adjust status by filing the FORM I-485 with USCIS concurrently with the FORM I-130. As to your sister, you can file the FORM I-130 on her behalf but a visa will not be available for over 12 years.Best of luck to you.