As child, with parents
Great-Great Grandma Riddle's son (possibly "Great Grandpa Riddle") is the likely identity of a young boy shown in a photograph with Great-Great Grandma Riddle (along with "Great-Great Grandpa Riddle", implied to be his father) shown at the end of I Am Rukmini Devi, after photos are shown with her and Great-Great Grandpa Riddle.
He is the only child shown alone, implying he might be an only child.
Yadina's great grandma could possibly be an unphotographed sister, or his eventual wife.
Strangely, she seems to resemble Riddles' dad's mom.