Russia is around -17 relations with us. He is NOT going to be "allied" with us any time soon. We may be able to gain some concessions and make sure he's never strong enough to hurt us but he will never be allied. The Norse Viking people have always been the ones we hoped to ally in Europe but they became TOO powerful and Buddhist befriending our enemies and becoming a threat... now... things could change.
Here is my basic plan outline:
Try to save Catherine; A = Alive, B = Dead
IF A Then Interrogate her; C = Intelligent and willing to work with us, D = Intelligent and not willing to work with us, E = Dumb Blonde and willing to work with us, F = Dumb Blonde and not willing to work with us.
If B Then Make it look like an Arabian-Ukrainian joint Operation instead of a English-Ukrainian Operation; G = Succeed and Come into the war on Russia's Side, H = Fail and finger of suspicion is pointed at us thus Declare on Russia and Arabia at the same time.
If C then negotiate a agreement that leaves Ireland and Moscow in our hands; I = Success and we keep our words, J = Fail then go-to D
If D then talk to the Khan of the Irish to see if they will become vassals if we get them Ireland back (so we can protect them); K = Success thus forcefully marry Khan and Catherine in both the Buddhist and Christian tradition. Then every Russian city we take that we don't want to keep can be gifted to the Irish stopping our over expansion costs. L = Fail thus Declare on Arabia to claim back Moscow for us to keep. Catherine stays hidden untill she is useful.
E = Dumb Blonde will do anything we want. But too Dumb to bargain with directly, Thus will depend on negotiations with Peter; M = Peter refuses to leave Moscow and Ireland in our hands thus assassinate him and place Catherine on the throne as our vassal, N = Peter agrees and we help Russia against Arabia in exchange for Ireland. Catherine is married to an Englishman for insurance.
F = Dumb Blonde and now willing to help us, she will probably blame us for everything and thus sour any relations with Peter. Forceful marriage is the only option with political trickery to gain a political cause to attack who we want.
End Plan outline.