A Milford couple are under arrest for allegedly abusing their 11-month-old son, according to police.Jeremy Coleman, 25, and Helena McKinstry, 22, are expected to be arraigned tomorrow in Milford District Court on charges of assault and battery on a child causing substantial injury and wanton or reckless conduct creating risk to a child.Coleman is being held on $20,000 bail. McKinstry is being held on $10,000 bail.Milford police said the boy and his twin sister are in the custody of the Department of Children and Families.