Happy to give details of how we used to do it if you're interested, but I don't want to read like I've barged in on your thread and started telling you how do things! I'm really just here to enjoy the cute babies since I'm not doing any lambing work this year myself
Occasionally if one wasn't being a very good mother at first, we'd try putting one of the sheepdogs in a crate in the pen / jug next door. Often that would either make her protective maternal instincts kick in, or she'd at least be distracted enough to stand and let the lambs get a drink without pushing them away.