Download the Flanders one and import the flags and all instead of NEw Spain (use New Spain's tag). Also get the few leaders from there and monarch. Use an id from New Spain. Change the config.csv file for nation name. Edit revolt.txt for New Spain / Flanders (380) and Holland if u want (to exclude Flanders) and dates. In the .inc file u don't have to change anything as it doesn't exist from the start. Big chance it'll popup during the calvinist revolts. Often reannexed though. U could of xure also add some colonial dynamism and so if u want.
