@Ankur Sanghi Yes it is possible, however editable sublist in Suitelets have an awful performance...

@alien4u - is it so bad that it shouldn't be considered as a viable option? If you don't mind, can you please advise what API objects / methods to use if I wanted to explore that?

Form.addSublist(options)

and

serverWidget.Sublist

...

Thank you! I will do a test for our specific case and see how that goes.