does his insurance pay for physical therapy? ideally you want your father to have a PT advise on his treatment. exercise, whether standing or seated or aided is critical in PD, he should be gettting a RX for exercise, your father should be referred to a PT in an ideal situation. having your mother/father join a local pd support group would obviously help, some are run by social workers very in tune with the local pd resources and what's best.

you can hopefully find resources at your state chapter.
APDA (National Organization)

The American Parkinson Disease Association is the country’s largest grass roots organization serving the Parkinson’s community. It is a 501(c)(3) not-for-profit organization and receives no governmental or public funding. Each year APDA contributes substantially towards both research and direct patient and caregiver support through the generous support of individual and corporate donations.

Phone: 800-223-2732 or 718-981-8001
www.apdaparkinson.org