Devi Champika
Kusha was married to Champika, daughter of Maharaja Bhurikirti in a Swayamvar. Bhurikirti had sent the invitation of Swayamvar to Shri Ram and he had taken his sons to the Swyamvar. Champika chose Kusha and they got married. Kusha got daughters from Champika.
Rishi Agastya told Shri Ram that Champika would never get sons and when Shri Ram will got to heaven (Vaikuntha), Kusha will get married to Kumudvati and Kumudvati would get a son named Atithi and he will be taking the lineage forward.
In the Swayamvara, Sumati, sister of Champika chose Lava as her husband.
Later, Lava also married Kanjanana, another princess.
Source- Ananda Ramayana
Mahadevi Kumudvati
Kusha while bathing in Sarayu river along with his wives lost his golden bracelet and he got angry. Suddenly Naga King Kumud along with his sister Kumudvati came from the river and he gave the bracelet and his sister's hand in marriage to Kusha. He gladly accepted and raised Kumudvati to the rank of Queen Consort. Later they had a son named Atithi who was jewel of both dynasties. Atithi married Princesses with his father's permission and later he was crowned as Prince Regent (Yuvaraj).
When Kusha died, Kumudvati followed him in death and Atithi became the next Raghukula King.
Source- Raghuvansh by Kalidas