Mom can file I-130 for your sister. Sister cannot legally stay in the US. Sister cannot work inside the US. They must leave at the end of authorized stay.
This is what we included:
Apartment lease with both our names & signatures
Joint bank checking acct statements since wife's arrival in June 2017.
Deed for new home with both our names
Mortgage Lender Letter with both our names.
Credit Cards showing both on joint account with same card number.
Amazon delivery label showing both names and our current address.
Wife's Military Dependent ID card showing me as the sponsor.
Tricare Eligibility Letter showing both of us together.
Military pay statement showing wife as my benefic.
Texas Health Care Directives appointing each other as sole health care proxy(Advanced Directives)
Our Texas driver's licenses with same address for both of us
2018 Joint Tax ReturnTax Returns
Pictures of us on special occasions here in the US.
Car Insurance Cards showing both of us as insured drivers for our car
Boarding Passes for Las Vegas Valentine Day Trip 2019
Utility application showing both our names for our current address