Ted, I'm sorry, but your example is a totally different situation.   To do what you are talking about requires realtime communcation between the machines, and an algorithm to synchronize the data dynamically into the same map.  Now that companies mostly have auto-steer nailed down, I predict this will be the next big feature introduced by Deere and AgLeader.

The task of compiling a set of variety maps collected many months ago, and potentially from multiple monitors or non-insight monitors, into a single variety map, and then loading it into the a yield monitor at harvest is much simpler.  Deere is often referenced in this forum as an examle of the least functional monitor... but you could do this task with the GS1.   The implementation in the monitor sucked for split planter work, but it worked just fine for single-variety regions.  

Given that Deere has this feature and Ag Leader has still chosen not to implement it, I can only guess that AgLeader found that 1) most people with an insight in their combines use the insight for logging their varieties (instead of some other solution) and 2)  most of their customers don't run multiple planters... at least in the same field.    Just my guess from the outside looking in.    And, i will also guess that you will see this feature added before much longer... but priority for hardware resources has surely (and appropriately) been greatest for things like Direct Command and enhanced guidance patterns.