It would be nice if the OP came back and answered some questions…
- Is this a court ordered legal guardianship you have...or just an arrangement with your parents?
- Will the parents be relocating to this new place as well?
- Will you and your spouse need to get new jobs if you relocate?
- Have you crunched the numbers regarding costs to relocate and paying school costs.
It sounds to me like this is all being driven by your siblings green card status…and she needs to come to this country to preserve that. But these other questions are important for YOU to answer.