My understanding of the facts follows: While your mother was alive, she provided your sister with a life estate in your mother's house. When your mother passed away, you and your siblings inherited your mother's house as tenants in common. The loan on the house still exists. Your sister is paying the loan. Your sister still lives in the house. Assuming my understanding of the facts is correct: Any of you as tenant in common owners of the house can petition the court to sell the house. All of you should work together to hopefully arrive at an agreeable resolution. Legal (real estate/litigation) counsel may need to be retained to help.
Legal Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on since each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship. A lawyer experienced in the subject area and licensed to practice in the jurisdiction should be consulted for legal advice. Circular 230 Disclaimer: Any information in this answer may not be used to eliminate or reduce penalties by the IRS or any other governmental agency.
The short answer to your question is that a judge could force a partition of the interest in the property and could force the sale of property held by multiple parties. You indicate that your sister has only a life estate interest in the property, it is unlikely that she can force the sale of the property if that is truly her only interest. The remainder beneficiaries are the true owners in property where another holds a life-estate.
A review of the actual deed will show whether she has any interest other than a life-estate, if it was drafted properly.
Your post doesn't have enough information to completely answer the question of whether you need a probate (estate) attorney or a real estate attorney. However, I would suggest that either could give you basic advice based on your specific facts. I also suggest that you start with the attorney who probated the estate to begin with.
This answer is not intended to be legal advice and does not create an attorney client relationship. The answer provided is only intended to be a general response based on the limited facts presented. I am a Florida attorney and only provide information based on Florida law. You should always confer with an attorney licensed to practice law in the state where the controversy exists, and not relay solely on any information obtained through message boards.
If you were to agree to pay the sister for her to move out it should be in conjunction with execution of a deed giving up her life estate. I don't believe you are entitled to partition the property when the sister has a life estate. The sister is entitled to the exclusive use of the property for as long as she lives. Even if she moves out of the property, she has full use of the property and if she chooses to rent the property she is entitled to all of the rent. She does not have to pay the other beneficiaries anything. The other beneficiaries, or remaindermen, will be entitled to possession or any other right to the real property after the sister dies.
No attorney-client relationship is created by answering questions in this public forum. If you wish to create an attorney-client relationship, you must contact me directly and sign a representation agreement. Answers are provided based on general ideas and an answer specific to your situation would require a review of all documents.
I am in agreement with Mr Chen's answer above, that barring any other damages your sister may cause to the premise, the tenant in common (sister) cannot force the sale of the life estate. However, you should seek legal counsel to discuss the duties of your sister in possession to the rest of you in regard to her upkeep of the premise including her continued payments on the mortgage, taxes and utilities and the split among long term vs short term capital upkeep and improvements such as the wiring, roof replacement, re construction, expansion and maintenance - this could give you a heads up in your strategy to be sure your sister follows the Florida law involved and does not permit the house to lose value for the future interest holders. Hope this helps.
An attorney-client relationship has not been established herein and must not be considered legal advice. Licensed attorneys in the appropriate jurisdiction must review all the facts involved and search out the best and most efficient method to proceed. If tax matters have been answered then the above cannot be used to avoid tax related penalties. Please act accordingly.