From the wiki Serbdom:
http://en.wikipedia.org/wiki/Serbdom
"The renaissance of Serbian nationalism after three centuries of Ottoman control of the Balkans came at the time of the romantic-nationalist Revolutions of 1848 in Western Europe and the 19th-century expansion and rise of a great Slavic Orthodox power, the Russian Empire, which has designed itself as a protector (and later liberator) of Orthodox Christian peoples (among Serbs, Greeks, Montenegrins, Romanians, Bulgarians, Slavic Macedonians) on Ottoman lands."
Well protector had many meanings

Annexation/influence maybe.
also :" In 1863, the Association of Serbian Philology commemorated the death of Cyril a thousand years earlier, its president Dimitrije Matić, talked of the creation of an ethnically "pure" Slavonic people: "with God’s help, there should be a whole Slavonic people with purely Slavonic faces and of purely Slavonic character"
Seems some ok with unification from Serbian side, as he is one of the important people in the timeframe.
One of the main reasons of Crimean war is Russia's desire to control Balkans, so I think they are ok with entry.
If Ottomans have a chance to be influenced by Russia in game turns I would say Serbs,Bulgars should have 1000 times more probability to be influenced/controlled by Russia.
Edit: Modovia,Macedonia and Serbia are minor organized nation in game, how is that possible?
They were not even organized/civil war lately. Macedonia should not be organized as ex: Belgium
