The John McGlothlin families are not the same. A John did come from Ireland but he is not the same as the John McGlothlin you mentioned. John, Robert B, and other are the sons of Thomas McGlothlin of Wythe co VA born ~1799-1800. You can find a good many of this family in Carroll co VA- basically right next door. Robert B for instance, Uncle Robb (to us)lived right next door and my dad knew him. I do believe John, his brother, named his son after him.
John Wesley is either John W or John B depending on the record
and just to confuse the matter I think there is another John Wesley about the same time. My John (W or B)is married to Margaret Safewright, sometimes called Mollie.
Does this help or confuse you even more? :-)) Pj Mc