License required for Replication Server and ASE for RSSD

Hello,

One of my customer is planing a replication system.

They use three servers:

Server1: ASE1 (primary DB)
Server2: REP + ASE (for RSSD)
Server3: ASE2 (replicate DB)

Replication Server 15.7.1 and ASE 15.7
I believe they need Platform Edition on Server2 to run Rep Server.

Suppose Server2 has 4 cores.
If they deploy 4 Platform Edition licenses, what happens on Srever2?

1) Both Rep Server and ASE (for RSSD) are authenticated.
2) Rep Server is authenticated, but ASE (for RSSD) is graced.

Do they need 4 PE and 4 EE (Edge Edition) for Server2?

Regards,
Kazuo Otani