You do indeed have a dependency between the region from which the FEPI CONVID was obtained: you cannot pass this CONVID around into other regions. It's not to do with the PassTicket security processing, just the way FEPI uses VTAM half-session support.
You are correct to use VTAM to define the emulated terminals in the place where the emulated transaction will execute, and acquire the Connection to these terminals in the AOR in which your application program issuing the XCF command executes. You cannot put a SYSID() on the XCF commands to use routing functionality.
There is no linkage between the terminal running a FEPI transaction and the XCF function: FEPI will quiet happily run using non-terminal attached transactions where the Convid is passed between these transactions (all of which, therefore, run in the same AOR).
Thus, you should continue to use your existing setup. Where you should make
changes is in the Routing URM to ensure that the transaction which is
using FEPI always goes to the 1st AOR it got sent to (in practice, this
means forcing it to a given AOR).
This was first published in September 2002