After further research, and assistance from
this post, I found a solution that worked for me.
Open DF settings, then go to Functions. From there, I used the Filter field and typed in 'save'. This filtered the 'Save Window Positions' and 'Restore Window Positions From Last Save' options.
I then highlighted each and clicked Edit so I could assign a key combination. Once the key combinations were set for each, I clicked Apply, then OK.
Next, I used the key combo I assigned to 'Save Window Positions'. Don't forget this step.
I powered off both of my monitors, then powered on the primary, then secondary. All my apps were slammed over to the primary monitor, as expected. I then hit the key combo to 'Restore Window Positions From Last Save' and B-BOOM! All my open apps went back to where I originally had them!
Thank you Display Fusion! This is exactly what I was looking for!
I hope this helps others!