Exceptions Web Flow - Using referenced web flows

The eSpace property "Exceptions Web Flow" only shows web flows that are local to a given eSpace. It does not show web flows that are referenced from other eSpaces.  We would like to set up a generic exception flow and have a number of eSpaces reference it. 

Is there a way to do this without having to create an explicit web flow in each eSpace?

I also came across this problem in 5.1 and raised it with support (ref #162334 ) and they said they created a Change Defect (!) and passed it to development... Hopefully we'll see it in an upcoming sprint but I don't have a timeframe.

In the meantime I'm creating minimal Exception flows redirecting to imported screen references - but note I've had trouble with originalURL redirection on things like Login flows and found the only workaround is to create a further redirector in the consumer eSpace (urgh!)  The sooner this is sorted the better!