Still working on this stuff. Just an update about my current thoughts.
1. “Paperwar”
a. New: It Is initially impossible to influence Spain. This can be unlocked with the paperwar event which can be played by either side. (Like the event when Belgium suddenly becomes able for influence which can be played by Entente, I can’t remember what it was called)
b. Added to CP event pool: When German Offensive in the West becomes static.
= Paris not occupied before winter or Moltke sacked.
So Germany is looking more offensively for an additional ally that could backstab France as you said.
OR: First French units enter German Hex (In case Germany strikes east and France is offensive. So Germany starts looking for a new ally that forces France to remove troops from the west to the south)
Both should be possible, otherwise the Spanish event tree would not be accessible at all if Germany strikes east.
c. Added to Entente event Pool: French government flees from Paris.
(= German offensive looks strong, unstoppable and France start searching for another ally that could help them regaining the lost territory.
OR: Italy joins CP. This then simulating that France is worried that a combined Italian German invasion into France would outflank them north and south. So France is grasping for an additional ally to rebalance. A successful German campaign in Russia often leads Italy joins CP, so Spain comes more into focus.
d. If played by any side: Spain can be influenced by both sides.
e. Starts the race for information superiority in Spain: Both sides can start influencing Spain.
f. The Text for this event is written neutral, as I don’t know who will play the event under which condition. I could change the text, but then it would no longer fit to all mentioned circumstances. Change it anyway if you want, I am not a native speaker so some things might sound ´too wordy´.
2. The side that plays it first gets 2D6 influence for free. (This is just to have a little bonus for being the first that launches a propaganda advance in Spain).
3. The side that reaches a total of 15 Influence first, gets an additional 30 influence for free. (This hopefully makes it more attractive to invest in Spain)
4. CP can gain 3D6 additional influence in Spain for a naval attack on Gibraltar with a BB, BC or Pre-Dread. (Once only, this is more as a show of force maneuver to show Spanish that they have the same enemy.) The good thing: CP gets influence for free, but at a risk that their ship will be trapped in the western med…France will see that happening, so there might be navel action on completion.) A symbolic attack would probably be enough; I think anything else would be a bit too overstretching. An amphib on Gibraltar would have been impossible, and I think it won’t work anyway in the game!?)

Pop up event “Your enemy is our enemy!” (Comparable to the ones when a city is captured)
Text: To gain additional Spanish support and attention, Central Powers launch a symbolic naval bombardment on the British enclave of Gibraltar. The Rock is covered in thundering smoke. Casualties are limited, but the message is clear: People of Spain, we are here! Deeply impressed, newspapers are flooded with pro CP headlines. “Libera Gibraltar!” The UK and Portugal react outrageous.
Effect: 3D6 free influence for CP on Spain + Portugal shifts closer to Entente.
5. If Spain total alignment +70 to CP: Germany has gained enough influence to successfully request the use of Spanish ports for german subs: The “Atlantic Submarine Base” Event is added to the event pool.
6. Event “Atlantic Submarine Base”
Text: As German submarines operate further and further away from their homeports, German Navy Command is desperately searching for new, forward based Atlantic logistic sights to threaten Entente convoys at range. Agents have secretly approached Spanish port authorities to gain their logistic support. As pressure on Spain increases, the ports of Cadiz and La Coruna finally become available for resupplies.
Condition: Spain Alignment +70 to CP
Effect: Both Spanish ports are open for German and Austrian submarines
Questions: (German submarines only, right?! Austrian submarines as well? How about ships? Ships would be great to do something with Gibraltar, but it would be very unrealistic as well and very offensive from Spain allowing that as it would be impossible keeping that secret. I suggest we start with German and Austrian submarines only)
Ger & Austria can still use ships once Spain has fully joined.
7. If CP achieve a miracle: They, somehow, capture Gibraltar. I don’t even think that’s possible. But if they do it anyway, they should be given the option to hand it over to Spain under the condition that they join the war. This should massively convince spain, so something like +90 Alignment towards CP. But I honestly can hardly believe this is actually even possible. (I will try now and test it)
8. Everytime a german submarine enters a spanish port, entente gets 1 influence in spain. (!?)
9. Question: What´s better, adding influence in an event or directly shift the alignment to one side or another? I would not mind removing all the influence stuff if that’s to complicated and just directly move spain closer to a side. I just thought that would be to quick and easy. Spain should not be cheap to get…they never officially joined the war, so it should still cause some efforts to making them join. That’s why I keep recommending influence changes only.