If you get a horoscope of a person who has some doubt about his birth time and therefore the birth lagna, start verifying by asking about his siblings. The question should be invariably be asked whether he is the first, middle, last or the only child of his mother. The stress here is on his being the eldest/middle/last or the only child of his mother. See how the rule of replication applies.
Read the book thoroughly and start answering the questions of the critics of astrology ask without understanding astrology through proper study and attack it blindly.
The simplest approach to settle it in the case of the eldest child is given. In this monographs to follow we will show how one become the youngest, middle or the only child of his mothe