Assign App to Display/Desktop

A similar question was asked a few years back but I can’t seem to find a solution to my specific question.

Context: I have a Mac Studio Max with three external displays running MacOS 15.3.1. In Mission Control each display is assigned a separate desktop.

Goal: Assign apps to a particular display/desktop so that when I log in to my profile or otherwise restart or power-up my computer the apps I’ve designated to open at start-up will always open on a specific display/desktop.

Problem: This ability exists natively in MacOS Sequoia. However, I can only seem to get the preference to display if I create a fourth desktop. However, I have no need for a fourth desktop.

Question: How can I assign specific apps to particular displays when each display only has one desktop?

You can’t. At least one of your displays has to have two spaces. Then you can do it.

That was my fear. Alas. :sob: