In Bhagavatham Kilippattu, Ezhuttachchan follows the version of Bhagavata Purana in Sanskrit available in Kerala at that time (in 16th century).
This version is not available in print
The Bhagavata Purana in Sanskrit available in print is the Northern version, in which some episodes are missing (compared to Ezhuttachchan's text )
It is likely that the manuscript of Southern version of Sanskrit Bhagavata Purana is available in some manuscript library such as GOML, chennai or Sarasvati Mahal, Tanjaore or Manuscript Library at Trivandrum ( The case is same with Mahabharata ) .
While the texts by Ezhuttachchan and Kunchan Nambiar are in Malayalam, Narayaneeyam and Krishnagiti are Sanskrit texts - not Malayalam.
It is likely that all these great scholars are faithfully following almost the same original source in sanskrit. It appears unlikely that all of them will add something of their own imagination . It is to be noted that in spite of being an abridged version Dashama skanda , Narayana Bhattatiri mentioned upashloka learning satvata tantra from Narada in Narayaneeyam
Another way to establish the existence of a distinct southern recension of Bhagavata Purana will be to check the retellings of Bhagavata in Tamil, Kannada and Telugu for upashloka
In this context , bala lila of krishna at Ambati is another example.
While the printed Sanskrit Bhagavata Purana gives only a few shlokas on bala lila, Cherushsheri(Krishna Gatha), Ezhuttachchan, Manaveda (Krishnagiti- sanskrit) and Kunchan Nambiar describe many amusing episodes in detail. These episodes are found in the Southern Texts of Harivamsha (printed as Appendix II by Bhandarkar Oriental Research Institute , Pune)