Can a co-signer who is on title and doesn't live at property force you to sell to get off loan?

My co-signer who is my fiance's mother doesn't live with us and doesn't make payments on the home , but wants off the loan terms due to personal conflict. She is on title due to being the co-signer , I am on title and her son on title. Could she force us to sell, even though we haven't missed payments or done anything wrong. She has hired an attorney and petitioning for a forced sale even though the house is worth less that we owe!