That is a very tough series of annexations :to cover --- here might be one way to do it -- you need to roll 12's 5 x to get this done -- but their is a plausible situation
1. You need a stronger AH which has the artillery it planned for 1916 to be ready in 14. You also need them to choose Russia as the primary adversary and be defensive vs Serbia. In this case they do well vs Russia and cause massive Russian causalities, and retain their core trained officers for the future. This will help keep Russia neutral
2. You need Moltke to not pull the corps east pre the B of M. You also need some luck (ie GB has a bit more panic and pulls the BEF pre B of Marne (they almost did) ) with perhaps the loss of the 5th French army. Also have the Germans use the original plan and take Netherlands.
2a. Have Russian admiral attack Sweden (that is the only way u get Sweden in on the war -- Have GB invade Norway and Sweden & German force them out of the war (Germans and Swedes invade Denmark to close the Baltic) in this way you have Norway conquered by Sweden as well as Denmark to achieve your objective.
3. GB gets caught and loses one of its BB or BC divisions (came close several times - you need more aggressive German commanders) so no Dardanelles
4. French withdraw west and lose Paris, AH success vs Russia, a naval setback (still dominate but a bit closer naval forces), and no invasion of OE, prob gets Italy into the war on CP side
5. In 15 French hammer its forces against Germans (get slaughtered just like real 15), Russian army series of defeats (this will hurt your Romanian situation because they come in on CP side).
6. France pushed back in 15 / 16 by Italy and Germany and forced to sign surrender. Part of the deal is they surrender their fleet to Italy
7. Italy,AH,OE, and French fleet takes Mediterranean (Malta, Gibraltar, and Egypt ?)
8. Belgium Surrenders, France Surrenders,
9. Russia Knocked out in 17 --- Russian fleet turned over the Germans
10. GB agrees to terms (per yours) with the OE, French, Italian, Captured Russian Black sea fleet, & AH fleet in Gibraltar as well as the German, Swedish, and captured Russian fleet in black sea
Any way lots of things going perfect for CP --- however i can see this is possible (JUST )