Seleucid Princess (Wife of Sandrocottus)
The information on wives of Porus is not available but he had sons who died in war with Alexander so obviously Porus was not a very young man when he met Alexander and as a king, he likely had many wives but the information on his family is not available.
The wives of Chandragupta Maurya are mentioned in Parishisth Parvan and Mahavansh Tika.
Chandragupta and Durdhara
Chandragupta and Durdhara were King and Queen of the Mauryan Empire. She is said to be daughter of his eldest maternal uncle who had come to Patliputra with the King’s mother. He wedded the daughter of his eldest maternal uncle and raised her to dignity of Queen Consort and she was mother of Bindusara. The name of mother of Bindusara is Durdhara in Parishisth Parvan.
Both sources mentions that Chandragupta had many wives and Durdhara, the main Queen , had died while pregnant due to accidentally eating poisoned food of Chandragupta. Her baby was saved through timely Cesarion. Chanakya used to mix poison in his food to build his immunity but without informing the King.
Nand Nandini (Daughter of Nanda)
A daughter of Nanda was one of the wives of Chandragupta Maurya. The marriage happened after he had defeated the Nanda King. Parishisth Parvan tells a dramatic story that she had fallen in love with him at first sight and he rejected her but later accepted her due to Chanakya. Most likely the marriage was a strategic alliance where chandragupta gained legitimacy in the conquered Empire and she could continue her royal life as a queen. There is no information whether they had any children or not.
Seleucid Princess (in Indian royal dress after marriage to Sandrocottus)
Seleucus and Sandrocottus had a marital alliance after their war. Sandrocottus is identified with Chandragupta Maurya. Seleucus gave up Kabul, Kandhar, Herat and Makran (Baluchistan) and in return got 500 elephants and a marital alliance.
Historians opine that a marriage happened between Sandrocottus and Seleucus and Seleucus gave one of his daughters to Sandrocottus as his wife. The princess was likely quite young when she got married. It was very unusual for a Greek king to marry his daughter to a non Greek king , so, it's likely was deliberately not recorded in Seleucid Chronicled, specially when he was trying to portray himself as supreme King in Hellenistic world.