What is the ruling on offering the funeral prayer for an infant girl who died more than sixty years ago and for whom the funeral prayer was not offered?

The questioner is not obligated to pray over his sister who passed away a long time ago, because a prayer is not offered over a grave after the funeral prayer has already been performed before burial, unless the deceased was buried without a prayer. The offering of a prayer over a grave is permissible only if a long time has not passed.