Add subpanel one2many field in Campaigns module

Hi, I’d like to add a one2many relationship between Campaigns and Products, and ‘Campaigns’ and ‘Events’

In a subpanel form, as far as I know, I should modify

suitecrm/modules/Campaigns/metadata/subpaneldefs.php

File, but I don’t understand which of these relations should I take as an example.

Could someone put me in the right direction on this?