I could see some very discreet negotiations with Slovene and Croatian organizations (not necessarily the parliaments) that would lead to Slovenia and Croatia declaring independence and being promptly recognized by both
NATO and WP countries. It might even be in the best interest of both blocks to have a neutral independent country or two between them - could Slovenia tacitly come under western influence, while Croatia being neutral and the USSR getting free hands in Serbia & Bosnia?
For additional fun, make the nuclear facilities be located in Croatia.