lostfan, WW1 began on 28th july 1914(day when AUgarian sent document to Serbia, in which is AU monarchy decided to began war against Serbia)....on 2th August 1914 Nicholas II declarated that Russia is in war, too. so, that are two different dates....
so, about Olga and Carol, Ithink they would be good pair, but Olga would gave Romania Heir, but, unfournatelly, Heir might be sick, because disease hemophilia, as her brother, Tsarevich Alexei.....