I don't know EXACTLY how it works -
but shouldn't the combination of NOT = { Core with event = XXXX work?
Ie. that the second claim can only happen when the first has already happened, and only to nations that do not have the cores yet.
That way, I won't have to wait till 1700 to get cores on provinces I conquered in 1425 (exagerating now, but you get the point)
It would even open up the opportunity to give you an extra bonus (since you managed a credible claim after someone else already HAD the claim)
but shouldn't the combination of NOT = { Core with event = XXXX work?
Ie. that the second claim can only happen when the first has already happened, and only to nations that do not have the cores yet.
That way, I won't have to wait till 1700 to get cores on provinces I conquered in 1425 (exagerating now, but you get the point)
It would even open up the opportunity to give you an extra bonus (since you managed a credible claim after someone else already HAD the claim)