Mental Competency

My mother-in-law is an untreated Schizophrenic. My wife & I are the only
family living in the state of PA. She is destitute and homeless. Her only
source of funds are from SSI. It has been impossible to get her into a
mental health facility involuntarily. Her health is declining and she has
been in-and-out of the hospital twice already this year. What is the process
to find her mentaly incompetent, so that we can start making decisions for
her wellbeing?

You have to have a court rule that she is not competent after reviewing the evidence. A family law lawyer could assist you--it is not an easy process.

And you could also consult with social services or senior services in your town to discuss as well as a first step.