majety

My son is born in jyestha masha and with jyestha nakshatram , he is the elder son. we had the match of a girl of elder daughter , here both are elders and my sons star is jyestha , please let me know whether it comes under TRI-JYESTHA Dosha or not ? Can he get married with a girl who is eldest daughter in their family? Please also explain Tri-Jyestha dosha...