Saṇḍilya gotra (let's know about our rishi and their devotion and their ancestor and lineage)
Asitha rishi's son -> Devala rishi.
Devala rishi's son -> Sandilya rishi
Sandilya is the great grandson of Kashyapa
Asitha rishi:
In ramayana period,
Asita rishi explained the King Janaka about the philosophy of rebirth. (Brahmāṇḍa Purāṇa, Chapter 47).
Also,
Asita was a king (later became raja rishi) of the surya dynasty, the son of Bharata, and an ancestor of Rama (avatar of vishnu)
Know about Kashyaba rishi, Asitha (raja rishi) till Rama lineage in valmiki ramayan.
https://www.proudhindudharma.com/2021/03/ram-parampara.html
In Mahabharata period,
Celestial rishi Asitha and his son devala, both participated in sarpa yagya as per the command of janamejeya (great grand son of arjuna). Other celestial rishi who were present are Bhārgava, Kautsa, Jaimini, Sārṅgarava, Piṅgala, Vyāsa, Uddālaka Pramattaka, Śvetaketu, Nārada, Parvata, Ātreya, Kuṇḍajāra, Kālaghāṭs, Vātsya, Kohala, Devaśarmā, Maudgalya, Samasaurabha. (Chapter 53, Ādi Parva, Mahābhārata)
Asita, the sage, got by the blessing of Śiva a son named Devala. (Brahmavaivarta Purāṇa).
Devala rishi:
Devala was the son born to Asita rishi as the result of a boon granted by Śiva.
Celestial rishi Devala, once came to kanchipuram and took holy bath in vegavathi (saraswathi river).
That time, a gandharva named "huhu" (musician in swarga loka) entered deep inside the river silently and dragged the muni's feet.
Devala rishi cursed him to become crocodile as he was trying to drag others into river for his mischievous play.
Gandharva begged the devala rishi to pardon him and get back to swarga loka.
Devala said "the day vishnu chakra cut you, you will be released from this curse and will reach your place and form".
After years.. indradhyumna a pandya king who installed vyuha, vibhava, prakriti forms of vishnu (jagannath) in Puri, Odisha (utkala kingdom) which later was known as krishna, balarama, subhadra, got cursed by narada to become elephant when he disrespected his arrival to his palace.
Narada also pardoned him and said he will attain moksha when vishnu appears and save him at distress.
Gajendra moksha happened at same kanchipuram. The lord vishnu appeared as ashta buja perumal (vishnu with 8 weapons with 8 hands) and saved gajendra and cut the crocodile with his chakra.
Thus vishnu made both rishi's words true.
Ashta buja perumal temple is must visit place in kanchipuram where gajendra moksha happened.
Raṃbhā, the heavenly dancer fell in love with devala rishi.
But, Devala did not reciprocrate her love. So, she cursed him to become crooked with 8 bends in body. When he became crooked thus he came to be called Aṣṭāvakra.
His curse got removed during krishna avatar.
Devala rishi met Śrī Kṛṣṇa on his way from Dvārakā to Hastināpura after the great war was over and questioned him why he did not stop this war and krishna explained the incidents to devala rishi in detail.
Sandilya rishi:
Sandilya rishi is associated with the Shatapatha Brahmana of the Shukla Yajurveda.
His teachings are in Chandogya Upanishad
Sandilya rishi, who desired to worship Viṣhṇu but not in the Vedic method for which purpose he even wrote a book to propagate non-vedic principles. For the above sinful action he had to live in hell and at last he was born as Jamadagni of the Bhṛgu dynasty. (Vṛddhahārīta smṛti)
Brihadaranyaka Upanishad states that Sandilya rishi was a disciple of Vaatsya rishi. He was also the composer of the Śāṇḍilya Upanishad.
Sandilya Bhaktisūtras (Aphorisms on devotion) are as famous as those of Nārada. He taught bhakti in a scientific way (by Śāṇḍilya science).
Sandilya rishi was instrumental in resolving certain metaphysical doubts of King Parikshit of Hastinapura and King Vajranabha of Dwaraka and he was instrumental to start idol worship of krishna bhakti after krishna avatar completed.
Read here to more about this...
https://www.proudhindudharma.com/2020/08/how-krishna-worship-started.html