Anjana,
For the first child we see the 5th house and for the second child we see the seventh house.
In our mother’s horoscope the 5th lord Mars goes into the 6th house indicating disputes with the first child.In the navamsa chart the 5th lord is debilitated in the 8th house with Rahu and in the Saptamsa chart 5th house and lagna lord are again afflicted which are all bad combinations for the first child.
Tell your mother to chant Hanuman Chalisa daily to reduce the evil effects.
God Bless,
Astrologer Akash.