Hi! I have a tiny, tiny little lamb, one of twins born yesterday and the mother has taken her twin who is much bigger and stronger and rejected this one so I am having to feed her as a pet lamb. The smaller they are the less they'll take. I've had this concern myself on a number of occasions with orphans. What I find is that the little ones have difficulty taking the bottle - it has to be almost forced in and then they suck for a few seconds and stop, having taken very little. However, like babies, they prefer, and are better off with little and often rather than 4 hourly. This one I have has kept me awake all night (literally). She bleets incessently around every hour and a half for food - takes a little and then bleets again for company (groan!). How old are your smaller orphans? - If they are under a week, sounds like they are normal. Also, the smaller lambs, especially those from multiple births, don't always progress as fast as singles or good sized twins. In a couple of weeks you'll see a big change. Its just that getting to that stage is a lot of hassle and worry. If your bigger ones want to go and run around and there its quite safe for them, then let them to have a run. Cheers and good luck.