I always find it trial and error when making rasmalai from milk powder - too much baking powder and the balls disintegrate in the milk and too little baking powder makes the balls hard.
I make mine with paneer now and it always turns out perfect. To make the paneer I bring some milk up to the boil, add a couple of spoons of vinegar/lemon juice and strain the mixture. The curds left are then kneaded until silky smooth and shaped into balls and put into milk etc.
iv tried this too ( many a disaster ras malai's from my kitchen, hubby has banned me from making any more cause he's sick of eating "gone wrong ras malai")
I Found that the balls were a little harder with this recipe, and also they were a little tasteless as they didnt suck up the sugar in the milk too well, then i tried adding sugar to the curd whilst making the balls, but it seems to long winded.