Forced land court partition sale

[Mr 12]

My sister and I are the only names on the deed for the house which my mother currently resides. She is legally entitled to remain in the home until she passes. Due to several factors, I denied their request to sign over the deed several years ago. I've since received notice from my mother's atty. requesting that I voluntarily sign over the deed {my sister has agreed} so she can sell the home, and if I don't she will take other legal action, further suggesting she will file a forced land court partition if I do not agree to sign. What are my options? Is the worst case scenario I would receive 1/3 rd of the value of the home? Is negotiation an option? I'm in Ma.

[buildersmate]

This is a UK-based site. You'll be lucky to find anyone able to comment on US law.