Trend plot overlay, time desynchronized

Hello Andrew & Co.

I need some guidance in an attempt to add some required functionality to my SciChart application.

A requirement has been brought to my attention where a user wants to do a graph over lay from a different time snap shot . This is useful for comparison reasons, where the engineer wants to compare a previous successful execution of a process with a current running one.

• One part of the solution is to save the dataseries info from a finite
  time period in the past.
• Second part is that the overlaid trend (dataseries) need to be time
  XAxis independent but YAxis relative.

I am looking at two different scenarios let me see what you guys think:

1. Overlaid historic static trend on existing chart surface
2. Historic static trend in a new chart surface (smaller format) on the
   bottom of the current chart surface being displayed

How should I best approach such an implementation ? The application is using the MVVM pattern. I have adhered to the pattern pretty religiously so far

Hopefully that makes sense to describe what I am trying to accomplish.
Appreciate your support and expert guidance in this matter

Thanks
Anders