Can an adult child take over guardianship now of a parent that has placed POA to another family member years before?

My Grandmother appointed me POA 6 years ago after deciding she was getting to the point where she needed someone to take care of her affairs when her eyesight and hearing diminished. Her children at the time were not willing to take care of her needs because of a family dispute. They left her in an assisted living facility and told her to fend for herself. She was scared and called me to help. I in turn called my lawyer to see what could be done to help her. He suggested a doing a durable power of attorney. So that is what we did. My grandmother was still able to sign her name and state what her wishes were. I was not at the facility when the document was signed by witnesses and her lawyer. Her children were notified by the administrator of the facility before this took place. No one came to stop the proceedings. No one made an attempt to contact her or myself. Now, she is 101 diagnosed with dementia and all of a sudden her children want guardianship of her. I was served court papers stating that they desired guardianship and that I desired to relinquish my POA. That was a false statement. My lawyer said to show up to court with my POA paperwork and present it to the judge. The judge said that POA had nothing to do with guardianship and that her children's stature of next of kin would be in their favor. I find out Monday what the court decides. We live in Michigan. I am not certain if that makes any difference. I am not familiar with the laws or bi-laws.