I have a two part question:
Facts:
Last week my wife became a citizen. We want to petition for her mom's green card. My wife also has a sister who is 20 years old, who is currently studying at a U.S. university. My mother-in-law currently has a multi-entry visa to the U.S.
Question 1:
Because my mother-in-law has a multi-entry visa, is it better to (i) apply for the I-130 while she is abroad, or (ii) have her enter the U.S. on her tourist visa and then file the petition as well as an I-485 (Adjustment of Status). We would need to go through the Nebraska Service Center. Which method would be faster/better?
Question 2:
I have heard somewhere that when a woman gets a green card, she is allowed to bring her minor children with her. I understand that my wife can petition for her sister's green card directly, and this will take like 8 years or something. Is it possible that if her mom gets a green card and my sister-in-law is under 21, that my sister-in-law could also get a green card at that time if we play our cards correctly?
I appreciate any help you can provide!

Facts:
Last week my wife became a citizen. We want to petition for her mom's green card. My wife also has a sister who is 20 years old, who is currently studying at a U.S. university. My mother-in-law currently has a multi-entry visa to the U.S.
Question 1:
Because my mother-in-law has a multi-entry visa, is it better to (i) apply for the I-130 while she is abroad, or (ii) have her enter the U.S. on her tourist visa and then file the petition as well as an I-485 (Adjustment of Status). We would need to go through the Nebraska Service Center. Which method would be faster/better?
Question 2:
I have heard somewhere that when a woman gets a green card, she is allowed to bring her minor children with her. I understand that my wife can petition for her sister's green card directly, and this will take like 8 years or something. Is it possible that if her mom gets a green card and my sister-in-law is under 21, that my sister-in-law could also get a green card at that time if we play our cards correctly?
I appreciate any help you can provide!