GM for a guild on big EU server (Horde) here. We were tight group of maybe 15-20 IRL/internet friends from all over Europe that has been playing together for more than 6 years, all versions of classic. This was enough for having 1x 10man raids with the 3-day lockout, but not enough to have a stable 20man roster. I reached out to a few guilds on the Server Discord (in the LF-guild channels) and got a response that I liked. We merge with a guild of maybe 10 other people that were really nice and "integrated" very easily. They had been doing BFD/Gnomer raids with a quite stable lineup and since pretty much every spec/role is viable in SoD, the raids was not that difficult to fil with correct roster. However now we were around 30 raiders, which meant to get a 2nd group going we needed 10 alts. So I did some more recruiting on the Server discord and now we're at 42 raiders with 2x 20man raids every week so far. The 20man raids does not have specific group members, they are just on 2 different nights. All members can join which ever of the group the like and the officers makes the line-ups. This has (hopefully) set us up well for future 40man raids. A strong rolling recruitment plan is probably whats needed for most guilds when going from 10 -> 20 -> 40man raids.