An excerpt from "Verse By Verse Ministry.org" entitled, "Who are the "children of promise"? states: " The New Testament uses the term “children of promise” to refer to all who are born again by faith in Jesus Christ, the Seed promised to Abraham. Therefore, all who are children of the promise are also those who have become children of God by faith in Jesus Christ." This article may be viewed at: Who are the "children of promise"?/versebyverseministry.org
Reference: Romans 9:8