So, how do Italy and Turkey react if the general European conflict breaks out in the middle of their war?
Italy would likely end the war asap and prepare for a major European war. whichever side they would join would depend on who is winning.
If we are talking about a war sprouting from the Bosnian Crisis it would look very similar to otl WWI.
Bulgaria would join the same side as Serbia (so entente) Due to first Balkan war not being over.