Do babies NEED the 'Junior' food?

My 2 new babies came with the mix they were weaned onto, but I will be changing them gradually over to the food I feed Roxy & Rory....which is P@H Adult Nuggets.
Do I need to put them on the Junior & Dwarf ones first or can they go straight to Adult?
They're 12 weeks old.

They can go on the adult my babies are on allen and page natural pellets as thats what all mine are on just remember to change them slowly and they will need a little more than your older bunnies for a while to build them up

OK thats great thanks, just seemed silly buying extra food when I have a 10kg bag of adult ones hehe.
But would of done if they needed it