Hi @nirmal_masilamani,
You can create a single elf for a multicore project. There is this example in community you can refer to: Example MPC5777C Single ELF multi-core Pin Toggling - S32DS Power 2017.R1.
It is quite old, but the same concept applies.
Other method can be creating binaries for all .elfs and merge them. But in raw binary does not contain info for addresses. Better idea is to create three s-records and merge it with srecord tools: SRecord 1.65.
I've also sent you a private message regarding an example routine for single elf on S32K358.
Best regards,
Julián