I asked an [OE/AM Synchronisation question on Stack Overflow][1] ages ago and despite Pete answer's I never got this clear in my head - but had to move on. Anyway, its raising its head again so wanted to check here.

Basically we're looking at two publishing targets, one for LIVE and one for PREVIEW/STAGING (where content editors can check content changes).

Our LIVE ASP.NET web application is the live site, where users can register & login (using ASP.NET membership) to access restricted pages - we use the AM API and store details in SUBMGMT, sync'd back to CM.

I'm interested to know opinion & the experience of others on how we'd approach this type functionality on PREVIEW/STAGING:

 - If we wanted to maintain fidelity and have registration & login
   functionliaty working on PREVIEW/STAGING we need a working AM API & SUBMGMT table. Is this best shared with live (green dotted line)? 
 - If we maintain a separate SUBMGMT table we'd need ultimately need a separate CM to sync them back to (green AM sync) otherwise PREVIEW/STAGING contacts would be mixed up with LIVE ones? Also you can only assign one sync target on a publication, so Id have to use another publication for the PREVIEW/STAGING AM sync.
 - Or should PREVIEW/STAGING somehow short circuit registration/login
   functionality altogether and be a pure content preview?

![enter image description here][2]


  [1]: http://stackoverflow.com/questions/9837661/oe-am-synchronisation
  [2]: https://i.sstatic.net/R3f9C.png