How to add a sublist in a subform based on other variables selected in the subform?

How to add a sublist in a subform based on other variables selected in the subform?

Hi ,

I am a new user to Zoho, and non programmer.

So far so good, and it is intuitive.

However:

How do I create a sublist in a "sub form" , based on whether certain variables in other parts of the sub form are selected?
The sublist I'm trying to use is similar to a multi-select list in forms .

regards
Stewart