I live with my parents and care for them and I'm concerned my siblings have taken advantage of my parent's finances. Do I have any legal power?

It depends a lot on who has Power Of Attorney and the mental condition of your parents. If you intend to go the attorney route, be sure you have some facts to go on. This could tear your family apart. However, if you are sure this is happening and that your parents are being taken advantage of without their knowledge, then you can see an elder law attorney. In the end, you parents have control of their finances unless they are considered by a court to be impaired, so take that into consideration, too.
Good luck,
Carol