Zoho recently added the multi-lookup type field to Zoho CRM, which allows you to create an N to N relationship between two modules by adding just one field.
Previously, users had to use a custom module. On the surface this seems great; however, if your users prefer the Zoho mobile app, be warned that this field type is not supported in the Zoho mobile app.
A multi-lookup field in the desktop app has a lookup icon that opens a search box. In the screenshot below, a custom module, Touch Events, has a multi-lookup field called Event Participants that links to the Contacts module.
You can see the lookup icon to the right of the field. When the icon is clicked, a multi-select search box opens, where users can then select multiple contacts to connect to the record.