I would check around. If your sister is willing to add you to the title, it could cost well less than $500. I normally charge $200 for this, in Michigan. The problem is...you cannot force your sister to do this. She is free to let the house be foreclosed if she wishes. That is your biggest problem.
*** LEGAL DISCLAIMER I am licensed to practice law in the State of Michigan and have offices in Wayne and Ingham Counties. My practice is focused in the areas of estate planning and probate administration. I am ethically required to state that the above answer does not create an attorney/client relationship. These responses should be considered general legal education and are intended to provide general information about the question asked. Frequently, the question does not include important facts that, if known, could significantly change the answer. Information provided on this site should not be used as a substitute for competent legal advice from a licensed attorney that practices in your state. The law changes frequently and varies from state to state. If I refer to your state's laws, you should not rely on what I say; I just did a quick Internet search and found something that looked relevant that I hoped you would find helpful. You should verify and confirm any information provided with an attorney licensed in your state.
As Mr. Frederick mentions, feel free to shop around. However your sister has the right to do as she wishes.
Matthew Johnson phone# 206.747.0313 is licensed in the State of Washington and performs bankruptcy, short sale negotiations, and estate planning in Whatcom, Skagit, Snohomish, King and Pierce counties. The response does not constitute specific legal advice, which would require a full inquiry by the attorney into the complete background of the facts and circumstances surrounding this matter; rather, it is intended to be general legal information based on the limited information provided by the inquirer; it This response also does not constitute the establishment of an attorney-client relationship, which can only be established after a conflict of interest evaluation is completed, your case is accepted, and a fee agreement is signed. Johnson Legal Group, PLLC
If this is the case there is no reason to keep paying for the upkeep. Tell her you will not keep paying if she does not transfer 1/2 of the property to you. By the way, you are not entitled to deduct the taxes you pay on the house on your individual tax return. Also, if she does agree you then are going to have to determine which form of joint property to use; joint tenancy or tenancy in common.
LEGAL DISCLAIMER Mr. Fromm is licensed to practice law throughout the state of PA with offices in Philadelphia and Montgomery Counties. He is authorized to handle IRS matters throughout the United States. His phone number is 215-735-2336 or his email address is email@example.com , his website is www.sjfpc.com. and his blog is <http://frommtaxes.wordpress.com/> Mr. Fromm is ethically required to state that the response herein is not legal advice and does not create an attorney/ client relationship. Also, there are no recognized legal specialties under Pennsylvania law. Any references to a trust, estate or tax lawyer refer only to the fact that Mr. Fromm limits his practice to these areas of the law. These responses are only in the form of legal education and are intended to only provide general information about the matter within the question. Oftentimes the question does not include significant and important facts and timelines that if known could significantly change the reply or make such reply unsuitable. Mr. Fromm strongly advises the questioner to confer with an attorney in their state in order to ensure proper advice is received. By using this site you understand and agree that there is no attorney client relationship or confidentiality between you and the attorney responding. This site should not be used as a substitute for competent legal advice from a licensed attorney that practices in the subject area in your jurisdiction, who is familiar with your specific facts and all of the circumstances and with whom you have an attorney client relationship. The law changes frequently and varies from jurisdiction to jurisdiction. The information and materials provided are general in nature, and may not apply to a specific factual or legal circumstance described in the question or omitted from the question. Circular 230 Disclaimer - Any information in this comment may not be used to eliminate or reduce penalties by the IRS or any other governmental agency.