So far DSS has been very active actually. I think we struck Greatbridge 3 times by now, took out 2 or 3 Sirion nobles who needed to go back home to refit. Problem here is, every time we walk into Greatbridge about 4.5k-5k cs peasants rise up to fight us. But as a one city realm, there are limited tactics you can employ of course. But I honestly doubt that Sirion can actually take the City.
As for Osslamar, IC of course Garas would deny any 'bought' argument. Nigel has a very legitimate claim on the region blablabal