Maximum number of Central Powers

With a pod no earlier than 1900, how many countries which were either allied or neutral IOTL be a part of the Central Powers? And please don't make an alternate WWI which takes place some other time, I'm talking about the WWI which started on July 28th, 1914 following a chain of events after Archduke Ferdinand's assassination.
 
- Netherlands could easily join to CPs.
- Italy respects its alligiance with CPs.
- Sweden could join to WW1 if admiral Nikolai von Essen attacks against Swedish navy and Sweden declares war to Russia.
 
I'm thinking China, US, Afghanistan and Iran could also become Central Powers. Could it happen?
 
Countries with significant pro-CP factions in 1914 included Sweden, Spain, Greece, Albania (if you can count it) and even Montenegro
 
-Italy stays on the Triple Alliance
-Sweden joins the CP and fights against Russia to get Finland Back
-Mexico accepts the Zimmerman Telegram
-A Third Boer War erupts and the boer republics (Transvaal/Orange Free State?) join the CP
-Iran joins the CP and attacks the British Raj
 
Italy - have them think there's more to gain by joining the CPs
Romania - they were up in the air OTL, so why not.
Sweden - Have the Russians clutch the idiot ball and attack them
Afghanistan - The Germans tried to convince them to join OTL
Ethiopia - OTL Darfur and the Dervish state (British Somali rebels) fought the British. The Ethiopians OTL provided some assistance to the Dervish State in 1915-1916. Maybe the Germans could get them to be a full participant.

China seems like a possibility too. The Germans considered giving them back Qingdao in order to keep the Japanese from getting the place and the Germans gave China a 6 million goldmark loan in 1912.
 
With a pod no earlier than 1900, how many countries which were either allied or neutral IOTL be a part of the Central Powers? And please don't make an alternate WWI which takes place some other time, I'm talking about the WWI which started on July 28th, 1914 following a chain of events after Archduke Ferdinand's assassination.
Afghanistan ?
 
Besides the ones already mentioned, if the US stays neutral, perhaps even a more neutral leadership to make it clear to that that wont change and Russia bows out in 1916 already, due to say a combination of Brusilov dying early and the Tsar deciding to cut his losses after a worsethanOTL performance. Then I could see even more long shots joining the CP in 1917 simply because they are clearly the winning side. Spain for example.
 
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