If multiple firms is managed by same proprietor. Then Esic Registration for 1 firm will work Individually or all firms will cover under it.
From India, Pune
If all firms are meeting the criterion of ESI applicability, all such firms need to be covered.
But as all firms are managed by one proprietor, you can apply for sub-code(s) for the firms
and ensure coverage.
From India, Aizawl
List_enclosure ESIC Registration procedure.PDF
ESIC NUMBER Registration.do c