I usually get mine down to three then two feeds a day over the first three weeks or so so they tend to self limit. My aim is not to have them sucking the bucket dry. This year, at about 5 weeks they limited themselves to 1.75 litres between the four of them twice a day and I'm now weaning them off by reducing the amounts and letting them suck the bucket dry (about 7 weeks). I know other people like to wean earlier from add lib.
Having said this, the lambs usually run with the odd ewe that's around with triplets that are being monitored and so not are the accessing food, hay/grass they have a role model and start eating really early on. This doesn't help you but this year the lambs stayed with their mum - she wanted them but was dry - and star that she is she mothered up the fourth one of her own accord.
I'm not going to give you advice, just passing on my experience, only you will be able to work out what's going to work best for you. Actually I will give advice - wash everything really thoroughly at least once if not twice a day and this is possibly the most important thing your friend will have to do.