Can I configure BizTalk Server 2013 to join an existing SSO system that is based on an older infrastructure?

I installed and am attempting to configure a BizTalk Server 2013 system to which we want to transition from BTS 2009. It will use a remote, clustered SQL Server 2012 instance that runs alongside SQL Server 2008 SP3 which serves the present-day production BTS 2009.

When I started to configure BTS 2013, I tried to join the SSO System already being used by the BTS 2009 machine. After entering the credentials for the domain service account {domain}\SSOService, I got this message:

The SSO master secret server '{SSO server name}' specified by the SSO database 'SSODB' on SQL Server '{SQL server instance}' could not be found. Without the SSO master secret server the SSO service cannot operate correctly. (SSO)

ADDITIONAL INFORMATION: (0xC0002A0F) Could not contact the SSO server '%1'. Check that SSO is configured and that the SSO service is running on that server. (SSO)

Could not contact the SSO server '{SSO server name}'. Check that SSO is configured and that the SSO service is running on that server. (RPC: 0x800706F7: The stub received bad data.) (SSO)

I haven't found definitive guidance about if a newer BTS like 2013 can join an SSO system that is based on an older infrastructure like SQL 2008. But I have found two posts with the same symptom as mine:

1. Someone upgrading SSO from BizTalk Server 2010 to BTS 2013 (but StackO won't permit a link to this xxx.social.msdn.microsoft.com.xxx post)
2. Someone, like myself, trying to join a BTS 2013 system to an older SSO system (in this case, BTS 2010)

The answerer to the second post says:

If I understand what you're trying to do is to make a BizTalk 2010 coexist with BizTalk 2013 which is not supported. So a BizTalk 2013 will never be able to join a BizTalk 2010 group. As a rule all servers in a BizTalk Group should be on the same version.

But that answer sounds like a misunderstanding of the question - the problem was trying to join the existing SSO System, not the BizTalk group.

So my question remains: Based on the operating principles of BizTalk and Enterprise Single Sign-On, is it possible to have two BizTalk groups (in my case, 2009 and 2013) utilize the same SSO system?

Configuration summary:

1. Trying to configure BizTalk Server 2013 to join existing SSO system
2. SSO System I want BTS 2013 to join is hosted by the SQL Server 2008 SP3 instance
3. BTS 2013 is hosted on Windows Server 2012 R2. The computer includes the SQL Server features that have to be present when configuring a multi-computer BizTalk environment (Client Tools Connectivity; and Management Tools -Basic and -Complete) installed from the same SQL 2012 SP1 image as the back-end cluster. (Microsoft documentation says the front- and back-end servers must use the same SQL Server version.)
4. BTS 2013 will use SQL Server 2012 SP1 on clustered back-end
5. Clustered SQL back-end OS is Windows Server 2008 R2
6. Clustered back-end hosts SQL Server 2012 SP1, 2008 SP3, and 2008 R2

The answer you found is correct

If I understand what you're trying to do is to make a BizTalk 2010 coexist with BizTalk 2013 which is not supported. So a BizTalk 2013 will never be able to join a BizTalk 2010 group. As a rule all servers in a BizTalk Group should be on the same version.

BizTalk servers work together as a BizTalk group, (even a single server is a group of one) and all servers in that group need to be of the same version to join that group.

Some services are only available within the BizTalk group. The BizTalk Messagebox is one of those services that is only available within the group. The same goes for the Single Sign On service, which is part of the BizTalk group, and only accessible for the nodes of the group.

I have never tried anything like this, but i would expect that the Single Sign On service from another group is not even accessible to a BizTalk server in another group, even when it uses the exact same version.