Please check out this video: The L1® Approach and the History of Amplification
You'll see that the L1 system was engineered as a personalized amplification system serving as both monitor and main amplification systems.
It turned out, musicians and others found lots of other ways to use the L1 system. As a result, our community of L1 system users includes DJs & KJs, duos, and bands using two L1 systems for the front of house system.
On larger stages, an L1 performer can use the L1 as a personal monitor as they always have AND send a line out to the Front of House system. I have done this many, many times over the years. How well that works depends on Front of House system and the sound engineer managing it.
When Bose introduced the F1 Model 812 and F1 Subwoofer systems, some people used them to supplement what they were doing with their L1 systems.
We don't often recommend adding an L1 system to a mix of several other active loudspeakers on a small stage, but when people have a problem ("... we still need more monitors"), we try to use what we have on hand. You asked how to make the connections; I was happy to do that.
May I have your permission to move this to the general community area so others can comment and share their experiences?