You've stumped me.I am sure that the James Whitney living with Peter Light in the 1850 census is Peter's brother-in-law.Are you sure your Ruth isn't Peter's daughter. The Lights commonly married their cousins (common for Brethren in that era).Peter had a nephew named Oliver Perry Light, the son of David. I can find no Ruth among the other Lights. You might try Frank Light, he has a huge database. I think you will find his address here on the forum.