King Robert Bruce established his family as the Scots royal family early in the 14th century. And his brother, Edward, became High King of Ireland a few years later. However, David II (Robert's son) died childless, and the crown passed through his half-sister to the Stewarts.
So, WI the Scots succession was a bit more secure for the Bruces? David had a twin brother who died in infancy; Edward had two sons that are of questionable legitimacy (no one's sure if he wed their mom or not) and was engaged to a de Ross girl when he died. Bonus points if we end up with a cadet line in Ireland that inherits Scotland.