How do I see all my interplanted crops on the Crop Map?

Turn on one option and you see in a second which beds carry a second crop, and which ones could. Open Options on the Crop Map and turn on Highlight interplanted plantings: companions come out in solid colour with their names, and main crops fade to grey.

To reach a companion sitting on a main crop, right-click where the two overlap and pick it under Select Planting. Unassign Planting takes the companion off without touching the main crop. The steps are in Place interplanted plantings on the Crop Map.