Maratha taking over the world

[Diocletian]

I tried to colonise India as France at 1935 today, and the moment I declare war, about 4 full-stack Marathan armies pop up in the Carribean and take literally everything but the windward and Leeward Isles. I think I can get them out of there fine, but I wanted to know how one could go about making the likes of Great Britain and United Provinces start colonising Maratha? I'm trying to give them one of the provinces I just captured, but until recently I was at war with both Britain and the Provinces, and they just won't accept it, even for free. If about three of the European naval powers started fighting Maratha head on for colonies, do you think they would be able to win, or would the Marathans just kick them out anyway?

As it is, it looks like I'm set to lose my really experienced full stack army, they're just getting swamped by Sikh Swordsmen and they are much stronger than I anticipated. I remember one game I was Austria and I gave the Marathans saxony because I knew the Prussians were about to steamroll me, biggest miscalculation ever XD

Edit: just to clarify, since I never had the commitment to drive a grand campaign till 1800; if Maratha get too strong, will they literally pose a threat to winning the campaign? Or is it just that they are annoying and kill all your favorite enemies ;)