Serbs didn’t “choose to share”. They too were forced into Yugoslavia thx to Brit pressure since the promise from 1915 was withdrawn.
Serbs weren't "forced" to do anything -- they were on the winning side of the war, when Croatia was on the losing side. The British could have cared less about what happened to Croatia post-war, they had their own worries. Besides, Dalmatia wasn't even part of Croatia until after WWII when Tito gave it to them.