Stolen Children From Mexico?

My grandmother's name was changed after she was brought into the U.S. from Veracruz Mexico. The people responsible for taking her out of Mexico were wealthy in Mexico and the U.S. They changed her name, placed her with other strangers and made her work as a servant from a child age 7 until she married at age 17. These people took other children, for what I have concluded based on the documents I've found. My grandmother had two sisters and one brother. One sister was with her on the ship from Mexico, but they separated them on the ship. She found her sister in 1970, but she never found the other two. She also never found out what happened to her parents. She was told that her mother remarried and had other children. She never found out why they were separated like that. We heard that her parents owned land and property in Mexico. Legend is that these people stole their land and owned it up until some years ago. I have not been able to find names for the great grandparents or any other family in order to complete my family tree.