Thanks! I've been feeding them 6 times a day, high protein only (chicken, lamb mince, egg, cheese, ham and smoked sausage (!!) for flavour, some lamb liver, goat's milk with cod liver oil) and they have some small lamb knuckle bones to chew on too if they want. Thought I would introduce carbs slowly, maybe some rice, in a week or so?
The amount of weight gain is rather unusual because they had room to gain - especially little Tim as he hadn't been eating much before.