Which two powers were the signatories to the 'Treaty of San Stefano' in 1878?

Serbia and Greece feared the creation of Bulgaria , because 50% of their territories were Bulgarian’s before the arrival of ottomans! So 30 years after that , the balkan wars began ! In the first war Serbia and Bulgaria made an alliance to fight together against ottomans . Because of the region , Buls did the most of the fighting , so Serbia promised to give Bul some of their territory that once were Bul’s and 1/3 of todays Greece . But they didn’t do it ... so thats what led to the second balkan war! Where Greece and Serbia made an alliance against Bulgaria , but the Buls overrun them . But there was another twist , Romanian army attacked Bul from the north while the whole Bul army was on south ... so Buls had to give up and lost many of the territories they aquired in the previous war.

and they all lived happily ever after

The Great powers UK , France , USA didn’t approve the extension of Russian power over balkans ... Where were the great powers when Constantinopol fall in the hands of the ottomans (except usa) where were they when ottomans sacked the whole balkans and killed 1/3 of christians there , when they took christian children from their mothers change their religion , trained them for their army’s and then send them back to kill their brothers and rape their sisters ? Russia wasn’t the help they wanted , but thats the only one they had !