Replication supported firmware

Hi

Is there any information about the firmware versions between replication primary and target?

We found the matrix but v8 or v9 isn't included in that.

Currently we plan to add new PS6210XS and make replication partnerships with PS6210E(v7.1.9) which has already replication partner with current storage group(PS 6210X v7.1.9).

Do we have to upgrade the firmware of backup storage?

Thanks