After looking at the event files, I think I have discoevred what the problems is.
the problem is in event 3620, for the Lat events file
the trigger command is before the country command.
That means that when the polish event is triggered, there is no country called Kurland.
I tried it out just as you decribed and Poland did not gain Kurland as a vassal.
When I moved the polish trigger to the bottom of the event, Poland gained Kurland as a vassal.
So to fix this issue, command triggers need to the bottom of the event choice, like in the below example, marked in white.
Code:
#The Fate of the Teutonic Order#
event = {
id = 3620
trigger = {
AND = {
exists = POL
exists = SWE
exists = DAN
exists = RUS
}
NOT = {
exists = KUR
}
}
random = no
country = LAT
name = "EVENTNAME3620"
desc = "EVENTHIST3620"
style = 2
date = { day = 1 month = january year = 1560 }
offset = 30
deathdate = { day = 1 month = january year = 1562 }
action_a ={
name = "ACTIONNAME3620A" #Polish-Swedish Agreement#
command = { type = removecore which = 276 }
command = { type = removecore which = 282 }
command = { type = removecore which = 275 }
command = { type = removecore which = 281 }
command = { type = secedeprovince which = SWE value = 276 }
command = { type = secedeprovince which = SWE value = 275 }
command = { type = secedeprovince which = POL value = 282 }
command = { type = secedeprovince which = POL value = 281 }
command = { type = country which = KUR }
command = { type = treasury value = 500 }
command = { type = stability value = 6 }
command = { type = independence which = PRU }
command = { type = add_countryculture which = baltic }[color=white]
command = { type = trigger which = 3470 }
command = { type = trigger which = 3220 }
command = { type = trigger which = 3290 }
command = { type = trigger which = 3407 }[/color]
}
action_b ={
name = "ACTIONNAME3620B" #Russo-Danish Agreement#
command = { type = trigger which = 3471 }
command = { type = trigger which = 3221 }
command = { type = trigger which = 3291 }
command = { type = trigger which = 3408 }
command = { type = removecore which = 276 }
command = { type = removecore which = 282 }
command = { type = removecore which = 275 }
command = { type = removecore which = 281 }
command = { type = secedeprovince which = RUS value = 276 }
command = { type = secedeprovince which = RUS value = 275 }
command = { type = secedeprovince which = DAN value = 282 }
command = { type = secedeprovince which = DAN value = 281 }
command = { type = country which = KUR }
command = { type = treasury value = 500 }
command = { type = stability value = 6 }
command = { type = independence which = PRU }
command = { type = add_countryculture which = baltic }
}
action_c ={
name = "ACTIONNAME3620C" #Die-Hard Independence#
command = { type = trigger which = 3472 }
command = { type = trigger which = 3222 }
command = { type = trigger which = 3292 }
command = { type = trigger which = 3409 }
command = { type = stability value = -3 }
command = { type = treasury value = -500 }
command = { type = religion which = catholic }
command = { type = domestic which = ARISTOCRACY value = 3 }
command = { type = domestic which = INNOVATIVE value = -3 }
command = { type = domestic which = SERFDOM value = 3 }
}
}