Where does Michael fit in your scheme? He's older than Ron, so your "Ron is the eldest son" point is not correct.
I'm gonna butt in...again.
There are those who are born the eldest, but do not hold the position of honor, so to speak, as the eldest child. A second born son, for instance, can displace a first born due to a meeker personality or favortism by a parent & become in action and recognition, the eldest son. Age does not always apply.