Probably many migrants would also come from Serbia and Croatia, as there already were family ties due to former Yugoslavian guest-workers being in West Germany, so there were connections already before the war broke out. But I think the biggest influx would be people from the former Soviet Union. Some of them came anyway under special 'contingents' (i.e. Russians with German roots, and Russian Jews). Without any restrictions, I'd say they'd make up the largest group - especially if you consider the economic/political chaos Russia was in during the early Nineties, and de facto civil wars in some CIS countries. And that might have led to bizarre political conflicts between the governing CDU and the oppositional SPD. IOTL, they were basically at odds with each other about who could come in. The SPD and the Greens were criticising Kohl for singling out the Russian-Germans, who were granted German citizenship easily and therefore - so the polemic went - brought back "heim ins Reich". Meanwhile, the SPD was originally against tougher restrictions regarding the asylum laws (which the CDU favoured), and it was the only party that favoured a proper immigration law (which the CDU and FDP rejected - they didn't want Germany to be seen as a proper immigration country with ius soli citizenship). So with, say, about 800.000 people from the former Soviet Union in the country - some with German roots, but the majority of them without -, both parties would probably be singling out 'their' favourite refugee groups, while proposing strict measurements against other groups later. Then there was also the problem with growing violent right-wing extremism, which would probably have intensified.