CAN ASTROLOGICAL PREDICTION/ ANALYSIS BE MADE BY LOOKING SOMEONE’S SIBLINGS BIRTH CHART
Yes that is possible in vedic astrology, the only issue is that the birth details of the sibling should be accurate.
In this kind of astrology analysis the native should give few of the events of life to the astrologer so that the astrologer can co-relate the event with the new horoscope made from the sibling’s birth details.
This kind of horoscope does give good predictions but instead one should can also try for horary astrology / prashna kundli.
In horary astrology the only issue is that the native need to consult an astrologer in person and can not put up their question on open forum for free prediction.
The other technical part is that every time the native visit an astrologer to get prediction from horary method, the astrologer will plot a new horoscope. The old horary horoscope is of no use once the prediction is already made. So every time a new horoscope is made and the old one is rejected.
The horary horoscope also give accurate predictions and this method is very useful when a person donot have any birth details at all and not even any sibling’s birth details also.
In deriving a horoscope of the native from his sibling’s horoscope, one need to understand the relationship well and accordingly see that same relationship in that horoscope and then rotate that horoscope of that house to make it as ascendant and thus one gets a new horoscope of the native from his sibling’s horoscope.