Re-reading my post, I forgot to say that I think the purchased land (that William Gelling's 1683 will is referring to) might be Ballamillaghyn Farm. He left his husbandry items to his underaged heir, who'd be son John aged 13. That's farming equipment.
So I think he's the beginning of the Ballamillaghyn group of Gellings, a very large group with hundreds of descendants today.