What are my rights?

I have equal power of attorney along with my sister in my mother's Will which was changed in 1997. My mother trusting my sister was doing right was coerced into signing a highly engineered Will which is dramatically different than the one my mother made out herself in 1994. My sister in decided when the Will was signed she was going to take the reins and by the end of 2010 using this Power of Attorney and working hand in hand with my mother's financial advisor has signed ALL my mother's assets into her name. I also have a 50% split in my mother's assets outlined in the Will. My sister nor the finanacial manager have to date provided me with any significant records concerning my mother's portfoloio or what has taken place with it since my sister has taken it over. I feel the financial manager is totally wrong in his relationship with my sister in letting her accomplish this goal while never once contacting me for my opinion. Do I have grounds for a lawsuit?