Family medicine provides continuous healthcare for the individual and family encompassing all ages and genders, each organ system, and every disease entity. Prince William Family Medicine - Manassas, An Inova Partner. 8100 Ashton Ave #101 Manassas, VA 20109. 8100 Ashton Ave #101 Manassas VA 20109. Get Directions Phone: 703-257-8090 703-257-8090 ....