It's difficult to advise without being able to put a hand on their backs to condition score. Mine are 11 days off the beginning of lambing and the singles are getting 150g nuts twice a day and doubles 400g twice a day. They're still out at pasture but with ad lib hay. There's one older, thin ewe carrying twins that's clearly got a problem with her teeth, judging by the way a lot of the nuts fall out of her mouth, and she's on 300g three times a day. Feed at this stage is unlikely to get laid down as fat but will go into the lambs. I've never had a problem with too-large twins, only big singles before I started this feed regime, which is why the singles' feed amount is less than half that of the doubles. This works for both my Down and Mountain breeds.