Adding Textbox in SharePoint Page for External users to enter their comments

Hello all,

We are trying to set up a SharePoint site and share it with external users, so that they can add comments to certain items. To do that, we need to add a Text Area in various sections of the page, so an external user can enter their thoughts related to a certain item. Customizing the SharePoint page allows us to add a Text box, but that is not editable once the page is published. How can we allow external users to type in the comments in the page?

Thanks,

Karthik