Radioss - SubDomain for analysis with SPH particles

When doing an analysis with a subdomain, Is the subdomain supposed to be exported at the same time as the main domain engine file?

I'm asking the question since when I launch the analysis with a subdomain card and the RAD2RAD card, I got an error message saying:

For multidomain computation, file subdomain_0001.rad must contain ''/RAD2RAD/ON'' card.

The thing is that the subdomain engine file (Subdomain_0001.rad) is not generated while exporting and then starting the analysis.

I Copied the engine file of the main domain and renamed it with the subdomain name and I changed the time step in the subdomain engine file. Not sure this is the correct wat to proceed.

Thanks for helping