Hi,
I got a brother and sister at about the same age and had the same issue. I gave them 120g betweeen them and the seem fine on this. Just recently I have noticed them eating their hay as well (they are now about 14 weeks), as I have started splitting it in to 2lots of 60g one lot in the morning to get them in to their run and one lot in the evening to get them back in to their hutch.
Hope this helps.
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