IMHO it can be done. But it works best in bigger tanks were they can mark out their own territory. It also helps if they go into the tank in already mated pairs. But in the long run, it's a very iffy situation.
My tank is only 60 G may be 58 . and the territories are quite close to each other. even though there was a conflict they never tore each other apart. The oscillarious got to gether easy and skunks were a little harder cus they were not exactly the same type. but lets see. How this goes. I have a back up nano tank in case things go wrong. but so far so good.
Not "impossible" as I've seen it done, if only short term. Unfortunately what I've seen with the aquarists I've known to try it it may work for a short time but sooner or later as the clowns mature territory issues arise. I still have not known anyone who's tried it to get to the point where the pairs are all breeding without loosing fish.
In my 210g, it never worked. Eventually one female killed the other or tried to. Granted, I used some clowns that were maybe more aggressive than should have. I have tried multiple times though. Different species. Took two years with one group. I think it could be done with the right clowns and right set up.
I’ve successfully done it twice in a 210 and a 270. Both times it was a group of six, all added as small juveniles at the same time. Each time they kinda of pair up and stake out their own section of tank.
I could see issues adding established pairs at different times....
just Luck probably....I had 3 dissimilar pairs in a 210, the largest were already established and I added 2prs later. Even after I lost 2 fish to jumping they remaining saddle back and percula ended up pairing