In OTL, during the crisis following the abdication of the Bulgarian prince Alexander, the Bulgarian regents offered the crown to the Romanian king, but he rejected it under Russian pressure. In any case, such a state would be exceedingly unstable and would probably collapse fairly soon due to contradictory interests.
Romans + Slavic Turks? Not really going to work, in my view.
There is no such things as Slavic Turks - it's a oxymoron. If you think that because the ancient Bulgars were supposedly Turkic (a disputed theory) the Bulgarians are somehow related to the Turks, do you also think that all Slavs are Russians? It's the same logic.
The Romanians are also not Romans, merely one of their descendants.
It won't work. Off the top of my head they're going to fight over empty Dobruja after all of the Turks there are, erm, "relocated"
Once I did a Nazi Europe map where Romania gets the bulk of Bulgaria. Being Slavs, the Bulgarians were genocided in the 1950s.
Why would they "relocate" the Turks? In OTL, though many emigrated, there are still many Turks in Dobruja (more in Bulgaria than in Romania). Also of course there were many Bulgarians and Romanians in Dobruja even while it was under Ottoman rule.