crossreferenced datapoints

I have run across cases where we need a replica datapoint to drive different behavior than the standard datapoint behavior.  I am normally told by LM support when I need this to create a new virtual datapoint equal to the original value and then use that to achieve my goals.  This sounds simple, but the truth is this leads to divergence from shipped datasources, which creates maintenance headaches.  If we had a way to crossreference datapoints in another datasource, we could achieve this in a much more manageable way with insulation from future DS updates.  This actually relates to other features I have requested (multiple thresholds for datapoints and linked clones, to name a couple), but perhaps in a simpler way to achieve these goals.

A simple example of this is the reboot alert.  I would like to know the following:

 * system rebooted (check, this is present)
 * system has NOT rebooted in at least timeperiod X (nope, would need a replica DP to create the threshold, diverging from shipped code)
 * system uptime is approaching counter wrap territory (similar to above, but now another replica DP is needed)

If I could create a new DS that is populated with references to other DS/DP values, then I could make this happen in a way that survives DS updates (in the general case).  

The next level of this would address alerts over longer periods by allowing the crossreferenced DP values to be functions, including "average over last N seconds" and so forth.