What is the legal process to get a detained mentally ill sister out of texas state hospital and get treatment close to family

My sister is disabled and mentally ill and was detained when brought to the ER. She used to work a few months ago but now she is out of work and is without a health insurance. As a result she is getting treated at a Texas state hospital. I would like to take her to Massachusetts and get her care there where there is more family support? How should I go about this?