Without [SIEGER] in the elves' file, nothing yet. With the [ENTITY_GROUPING:EVIL], embarking on top of an elven city leads a massacre... so they do attack. Only the goblins have sent sieges so far, and within a single sleep cycle of starting, so I guess the elves need it too.
Oddly with [ENTITY_GROUPING:EVIL], neighbor screen at embark only shows dwarves and the nearest evil entity, whether it be modded elves/humans or the goblins. Putting [ENTITY_GROUPING:EVIL] in the dwarves actually makes the goblins friendly to dwarves.
Embarked with 50 stone. Built a wall around my wagon 1st thing. Got a farm up 2nd. Siege came while everyone was safe asleep. Goblins killed all my animals that were walled out, but oddly leave the local wildlife alone. No caravans from humans or elves. Dwarven caravan didn't last long. Goblins somehow never eat nor sleep or drink. Even more arrive. About 3 groups of 40 goblins outside while my dwarves live happily in a sealed hole. Found the edge of the demon pit. Walled it off immediately. I'm tempted to slip a miner out while the goblins are occupied dispatching immigrants for me, and open up the demon pit to the outside while I'm still walled in. Will the demons take care of the goblins or leave them alone?
I'm going to add [sieger] to the elves and humans next and see what happens. Can I adjust the size of a siege force in the raws?