Chris Brown is pushing back against a custody request filed by the mother of his youngest daughter, Lovely Symphani Brown. According to new court filings, the Grammy-winning singer is seeking joint legal and physical custody of the 4-year-old after Diamond Brown recently asked a Los Angeles court to grant her sole custody. Diamond's filing reportedly requested both legal and physical custody of Lovely while proposing that Brown receive visitation rights rather than shared custody. The "Loyal" singer, however, is asking the court for an arrangement that would give both parents equal legal rights and parenting responsibilities involving their daughter. Chris is also requesting that each party be responsible for their own legal expenses related to the custody dispute. Diamond previously asked the court to order Chris to cover the costs associated with the case. The legal battle follows months of public tension between the former couple.…