The answer to your question is yes ... and no.
You can share data over ODBC between the FileMaker 11 and 12 databases. However, you can't drop a table occurrence of a FileMaker 11 database onto a version 12 database graph to form a relationship, because ESS doesn't support FileMaker as an external data source. You'll need to set up an import of version 11 data into a version 12 table. Perhaps a scheduled import using server-side scripting?
My approach to a similar problem that you face has been to buy a Second hand MacPro specifically for FMS 12. There are plenty of Quad-core models that have come off 3 yr leases, are reasonably priced and readily configured for excellent FMS 12 performance.
This has given me a server for the new FMP 12 files and others that have been migrated in an orderly manner.
I think you misunderstood my original post. I do have 2 servers.
FileMaker Pro Server 11
FileMaker Pro Server 12
The problem is, that I have several databases that use other databases as table occurances.
I have a Special Education Inventory database that uses our Student database as a table occurance. I would like to move the Special Education Inventory database from the FileMaker Pro Server 11 to FileMaker Pro Server 12. BUT, I cannot, unless I also move the Student database.
At this time, I cannot do that. The Special Education database is only used by a handful of people, of which I can train them to use FileMaker Pro 12. The Student database is used by about 100 people. I cannot train all of them to move to FileMaker Pro 12 until summer.
I was hoping to gradually move some databases over to 12 and leave the others on 11, but NOT being able to use a FP11 table occurance in a FileMaker Pro 12 database is limiting my transition.
We've done several of these transitions. You have a few choices:
1) Hold off on doing the transition until you're ready to move the entire solution. (That's typically what we've done.)
2) Do an export of the data from the version 11 portion to some format that both versions understand (XML, CSV, etc.) and then import the data to the version 12 portion.
3) Create a duplicate set of tables in the version 12 portion and use ODBC to import the records directly from the version 11 portion on some regular frequency.
What choice you make will depend on your business model and specific needs. In cases (2) and (3), you'll be creating a data mirror of the version 11 system. If you need two-way communication, it gets a lot more complicated; you'll have to set up a synchronization protocol over ODBC to keep the two systems reconciled. On the other hand, if you just need to see the version 11 data in the new area, then a simple one-way data mirror will work fine.