HRS is a great source for information about rabbits. But
I don't agree with giving babies and youngsters unlimited pellets. It's not good for them if they eat too much (cecum poos, diarrhea, overweight, colic etc). If you know what their parents look like, or you can tell which breeds they're likely to be a mix of - you can estimate their adult size and weight. Or you can post i picture of them next to you for example to compare size with. If they're going to be about 2 kilos when grown up, 40 grams of pellets a day for each of them is a good amount. A 2 kilo rabbit should put on about 100 grams a week, untill it's 4-6 months. After that the weight curve will not be as steep. It's useful to weigh them once a week so you can make sure they're putting on enough
Also I would recommend oxbow basics 15/23 for babies and young rabbits (up to 6 months), because this feed gives baby best prerequisite for healthy growth. But of course, other feeds are ok too