Packages without the PM intervening between translation and revision phase

We have a new client who works with Trados WorldServer and I'm searching for the best workflow. 

At the moment, our biggest clients send us sdlxliffs and tmx files with exports from their TMs. We simply upload them on our platform and the translator delivers directly to the reviser, without the PM intervening. I've tested packages in the past, but it didn't seem to win us any time, especially not if the translator sends a return package and the PM has to create a new package for the reviser: it's extra work and the reviser has to wait, so we prefer to work with the sdlxliffs.

Internally we use Trados 2017, the reason we haven't updated yet is tmx files. Apparently there is a workaround, because they're not supported directly anymore in Trados 2021. Again: extra work for us if we would update. Will the tmx feature be re-introduced please? We get them from our clients constantly.

Back to the original question: if we send a Worldserver package to the translator, what should he/she deliver to the reviser that the reviser can read without us intervening? Alternatively, can we just unpack the package, send the xliff and TM and then create the return package with the revised files?