The flags pool is expandable. It's no problem to install additional flags or nations...
"We already have the Nationalist Spanish, it's right between the Dutch and Republican Spain flags ..."
No, that's not quite right ... I must admit, I did not in this case clearly expressed. The flag of the "Nationalist Spain" (1936-1938):
The flag of the "Spanish State" (1938-1945):
I hope the difference is recognizable ... Before it comes to further confusion, I will give an explanation of each new nation:
- Czechoslovakia - Fall Grün/ Green: the hypothetical invasion of Czechoslovakia (1938)
- Finland - Winterkrieg/ Winter War: the military conflict between the Soviet Union and Finland (1939)
- Denmark - Unternehmen Weserübung: the real invasion of Denmark and Norway (1940)
- (Franco) Spain - Unternehmen Felix: the Spanish/German joint plan for control of Gibraltar (1940)
- Portugal - Unternehmen Isabella: the hypothetical invasion of Portugal and Spain (1941)
- Ireland - Operation Green: the hypothetical invasion of Ireland in support of Sea Lion (1940)
- Iceland - (hypothetical) Springboard to the U.S.
- the Kingdom of Egypt - (hypothetical) North Africa, German troops fighting for, after a successful battle at El Alamein, Egypt ...
- Ukraine - inserted at the request of an individual... Ukrainians support - at least initially - the German side
- the Empire of Japan - axis partner
- the Republic of China - a secondary theater of World War II
Because of the fish-eye roundels ... yes, they do not convince anyone!
Flags with a slight fish-eye effect had an idea for "Legacy of Versailles", which it has not made it into the project. I have operated so little mod-recycling... I will soon provide an alternative view...
(1937-1942) or this 
(1942-1947)?