United Federation Starfleet “Task Force” events provide the opportunity for each ship or space station to participate in multiple roleplay missions. These missions culminate in a group RP mission that can involve all ships and all stations. Task Force Phoenix took place in October, 2019. Here is some information and a link to the stories that resulted from the individual missions.
After the destruction of Romulus there was a void in the Romulan Empire. Empress Sela attempted to consolidate power but there was another faction that wanted to form a new Romulan Republic.
This power struggle eventually dragged in both the Federation and the Klingon Empire. Seeing the writing on the wall, a large number of ships fled to the Delta Quadrant and found an area to carve out a new Empire.
Over the course of the last decade or thereabouts, the Romulan Star Empire has been rebuilding. This includes developing their new home world, constructing outposts and new ships, making alliances with worthy partners and conquering those who are deemed unworthy. This has helped them build a significant “slave” workforce.
Here is a link to the UFS Wiki article on Task Force Phoenix.