Okay, I have been keeping quiet about the Dutch questions because I have been playing with the Netherlands Fight Back Expansion for a while and had not gone back to the basic rules for some time.
I think that the relevant rules to consider are:
Great-Britain NRS (v3.5) :
Dutch Colonies : If Axis or Comintern declares war on the Netherlands, Netherlands becomes Controlled by or Aligned to Great Britain at the end of the Combat Phase. Once Aligned, it may distribute this income as it sees fit to itself, FEC or ANZAC.
Peactime Income Increases
Germany or Italy declares war on any neutral nation in Europe : +2D12 (each time)
Japan declares war on neutral (including China) : +2 (each time)
ANZAC NRS (v3.2)
Axis or Comintern declares war on The Netherlands East Indies : +3 (once)
FEC NRS (v3.4)
Japan declares war on any nation : +2 (each time)
US NRS (v3.4)
Japan declares war on British Commonwealth or France : +5D12
Japan declares war on any other neutral : +2D12 (once)
Germany declares war on British Commonwealth or France : +5 (once)
France NRS (v3.5)
Germany or Italy declares war on any other nation : +2D12
Germany or Italy declares war on British Commonwealth : France moves to wartime Income
Japan declares war on neutral nation or China : +1 (each time)
Rule 4.4 :
Once Aligned a Minor Power and its units become part of the Major Power for all purposes and ceases to exist as a separate nation for the rest of the game.
The obvious danger to avoid for the Axis is that a Japanese attack on an Aligned Dutch West Indies (i.e. for all purposes Britain), will trigger the +5D12 for the USA. So Min. 5, Max. 60, AVG. 32.5) and you are also declaring War on the Commonwealth.
However, if Japan attacks a neutral Dutch instead, the effect is far less imposing (+2 GB, +3 AZ, +2 FEC, +2D12 USA, +1 France). Min. 10, Max. 32, AVG. 21.
On the other hand, if Germany attacks an Aligned Netherlands (i.e. Britain), the Commonwealth and France can go to War, but the USA only gets +5.
If Germany attacks a neutral Netherlands, the effect is GB +2D12, France +2D12 and no effect on the USA.
Save for the 5 US increase, the German invasion will likely mean war with France and GB in both scenarios.
If the Axis want to coordinate an attack on the Dutch, I think that it’s much better for Japan to go first and Germany second than the other way around. You are trying to delay the US coming to war, which is the game changer in Global War.
And to answer the @manincellv questions :
If the Dutch Align with the British upon a declaration of war by Germany and subsequent capitulation, does:
Does the UK now control all Dutch ships and forces in
A. English Channel and
B. Dutch East Indies and can now move them?
Yes to both (Rule 4.4)
Are all these units replaced with British units?
Yes (Rule 4.4. and Appendix B(2))
Does the UK collect income from the DEI?
Yes, if it is in control of the territory (Rule 11.6)
Do the Dutch make an recruitment roll?
No, only Controlled minors do this (Rule 11.5 and Table 4-2) unless otherwise stated in the rules
How does this rule 4.12 Minor Power Colonies affect above?
In your example it doesn’t since the DEI are already Aligned to Great Britain