Yea, it's specifically a Portuguese problem too. Nobody else goes on a rampage releasing dominions, the only comparable situation is when Netherlands releases South Africa if it gets a foothold in its core areas.
Anyway, ran Sweden->Scandinavia (aka RUS GENOCIDE) campaign and Confederate campaign recently. The system really works a lot better now, CSA managed to get #1 industry and only ever had Laissez Faire until 1910s when the Brothers of the Revolution won the elections (and consequently made the economy provide surplus), and in case of Scandinavia I maintained a Laissez Faire economy from late 19th century to late 1910's when I decided to let the socialists stay in power (and to my surprise I did manage to fix the huge deficit with State Capitalism), finished as #1 industry then too (and this was with only 150 units of my own coal production, thanks to huge colonial holdings in Africa).
CSA campaign was deliciously imperialistic, by the end British were completely ejected from North America outside of Halifax, CSA stretched from Alaska to New York to Durango (Cuba was conquered with the Kwan event, which really shows the benefits of the ticking warscore); and in case of Canada there was only annexed Kwanada and a free Quebec. I also added some crossing over for Kwan events to CSA (namely Indian Wars) and a special post-emancipation decision to add Afro-Americans as an accepted pop so all them niggas don't just assimilate overnight. Sadly I never managed to get an Afro-American majority province around Great Slave Lake. Generally little overseas business was done, focus was always on the immediate borders, with after the Union being driven out of Pennsylvania the attack shifting against the British for the nice real estate up North and East of Northwestern Territories and Columbia (which were colonized prior to Brits early game, and in other case gobbled up when the moment was presented).
In case of Scandinavia, the Embrace Estonian Culture was ported from APD due to how much I like it. The Nordic multikult paradise saw immense population growth thanks to early swindling of my way to Universal Healtcare cap, which was very helpful combined with territorial conquests and three Baby Boom events. By the end, the border in the East was Tver, Novgorod, Lietuva, with Belarus, Potatoland, and Ukraine as liberated nations, and nearly half of Africa under Scandinavian multikult rule, plus Hamburg, Lübeck and Kiel added to the loving multicultural embrace (or more accurately, "DU ÄR SVENSKA POJKA NY" as a method of preventing German Unification FOREVER). Germany and Italy never unified, Hungary was freed from Austria, Romania never unified (thanks to my copious help for Hungary after solving the Crisis in their favor to free them), and the GP landscape was unusually altered in general (final make-up was Scandinavia as #1, United Kingdom as #2, Kwa as #3, Japan as #4, China as #5, Prussia as #6, France as #7, HUEHUEHUE as #8).
One thing I've noticed is that it's advisable to geld a civilized China by Liberating as often as possible during Crisis situations. Nanfaren countries are especially good for this.