Politics has always been a trigger that sets off a chain of events, and the change in demands from Alpha Kingdom directly accelerated the alliance process among the five nations.
Sometimes talking about money does not hurt feelings. In politics, free is always the most expensive.
With compensation, it's a fair trade. The political status within the alliance remains equal.
Unconditional military help? Alpha Kingdom dares to offer it, but the three kingdoms dare not accept it!
It's easy to invite the gods but hard to send them away. If things aren't settled in advance, the deployed military instructors could easily become military infiltrations.
With the entire military system branded with Alpha Kingdom's mark, how can there be independence in the military, not to mention in politics?
Once you become a subordinate, it's not something a little bit of food and money can resolve. Only in a dire necessity would a great nation willingly submit to another.