But to do that you have to own "surplus" territory, meaning a province that isn't part of your victory conditions (or you're willing to get back later in the game) and isn't critical to your economy or war effort at the time. It wasn't really an issue when I was playing Great Britain; I owned all of North America north and east of Texas except the Inuit territory and every island in the Caribbean.

As the Dutch, it is an issue. I'm not conquering territory; I've been purchasing it, so almost everything I own is required for my victory conditions. Gujarat I conquered when it went rebel, it turns out there's no diplomacy hit for taking a rebellious province. Bengal I purchased just to get a foothold on the subcontinent and it's fully stocked for recruiting troops, plus it's adjacent to Hindustan which I have to own to win.

So far, I've taken Gujarat in the manner mentioned, took Leeward Islands and Trinidad & Tobago from the pirates, Iroquois Territory after they declared war on me, Quebec after the independent nation of Quebec declared war on me, and I just took Tunis from the Barbary States after marching right through Algiers and leaving it alone for now. I need 25 territories, 13 of which are specified. I currently own 20 I think. As Britain I needed 35, and I had 45 by 1760, so I had extra I could trade if I needed to. Right now I can't afford to trade 1:1 unless it's a victory condition and I can replace what I'm giving up.

Gujarat wasn't a victory condition while New York was, plus I was hoping that giving the English a foothold in India plus a cash infusion would cause them to recruit troops there and step into the stagnant conflict between the Maratha and the Mughals, thus giving me an opportunity to buy either Bijapur or Hindustan from someone who didn't have it as their capital. That hasn't worked.