Let's say you always want to ensure your team adds the extension cables when adding a speaker to an order, but you want the speaker podium to be optional.
When editing the speaker, click into the Relations tab and click 'Accessories'

You'd mark the extension cables as a 'Required' and 'Hidden' Accessory. Marking an item as 'Hidden' will ensure the client doesn't see or be charged for it, but your team will still see it on their pull sheets. You'd leave those checkboxes blank for the speaker podium.

When you add Speakers to a project, the 12-foot power cables are automatically added, and the Speaker Podium is displayed as an optional accessory when you click the "View Relations" button.