Hello Christian!
Nice to hear from you and your work after so long time
Please do not forget the NSGr.7 in your work!
This unit never operated with Fw 190. Here are some lines from my Do 17 book which concern your question:
On 23 December, as a part of HZL reorganization Kroatien Kampfgruppe 1 was established and 15.(Kroat.)/KG 53 became 1./Kro.KGr.1, while 15.(Kroat.)/KG 3 of Oberstlt Milan Hetenyibecame 2./Kro.KGr.1. Hetenyi’s unit was formed on 15 March 1943 and after training with 10.(Erg.)/KG 1 at Schaulen and FFS B.6 at Kolberg was supposed to receive Ju 88’s and deploy them on the Eastern Front. Instead, it returned to Croatia.
On 1 April 19441./Kro.KGr.1was renamed into 1./Kampfgruppe Kroatien and by the end of the month Zemun became its main base. By that time, unit was brought into some sort of resting status as it barely conducted any combat flying. Still, on 28 May it celebrated 3.000th combat sortie at Lučko. During that month 1./KGr.Kro. received several Ju 87 Stukas of B and R subtype.
On 21 July, gen zrak Vladimir Kren officially disbanded ZMP. Airmen which opted to stay in Luftwaffe were transferred to newly-formed Hrvatska zrakoplovna skupina, from which two Staffeln, one with fighters and another with Stukas, were to be made operational. On 30 July five remaining Dorniers and four Stukas went from Lučko in direction of Königsberg (today Kaliningrad) in East Prussia. Pilot por Albin Vouk and his crewmembers vod Andrija Pavišić (RO), vod Ivan Pernar (RO), vod Antun Jozin (RO) and vod Jusuf Ustavdić (MG) had different ideas: they turned Do 17Z-5 Z8+AH W.Nr.2899 towards the Adriatic and after uneventful flight crash-landed near Cerignola in Italy.
Remaining Dorniers were exchanged for Stukas at Königsberg as legionnaires formed Kroatische Schlachtstaffel beim Stab/SG 9 (Pz.),lead by Hptm Franjo Gospodarić,at Schippenbeil. On 1 November all unit’s aircraft were deprived by the Germans, the consequence of defection of commander and another pilot from the neighboring HZL Jagdstaffel. All men were sent to infantry and subsequently deployed in trenches on the front between Frankfurt am Oder and Szczecin. After great difficulties and real ordeal, most of them managed to return to Croatia by April 1945.