@cindo – I also welcome you to Mayo Clinic Connect. I am the mentor for the Lung Cancer Group for Connect. You might want to join in our discussions and also see if they help answer a lot of your sister's questions.
I also have NSCLC stage 4A. I have a lung cancer called Multifocal adenocarcinoma. Although I am stage 4 the A is for non-metastatic cancer.
It depends on where your sister lives or where she is able to travel to where she wants her second opinion to come from. I have been treated at Mass General on the east coast.
Please let me know if I can be of further help. I'd love to answer any questions that your sister may have. DO you live with her? Other than you does she have a support system that can drive her or stay with her if she needs help? How is your sister feeling? Other than her lungs where is your sister's cancer?