[member=217017]louwxlls[/member] what a shame you didn't post this earlier. We had our first ever rejected lamb this year, one of twins. I was very aware of the 'what shall we do with it' dilemma so came up with a scheme. The ewe and her accepted lamb was penned (in our polytunnel, with the lockdown hens) then we made another pen onto the end of the ewe's pen for the rejected lamb. The ewe had rejected her viciously, and being a 4 horned Hebridean it was quite dangerous. We fed the lamb in the pen and put her twin in with her for playtime a couple of times a day (the sibling bond is much stronger in sheep than mother-lamb). The ewe stopped trying to kill the lamb through the bars and watched carefully as she was fed. We brought the lamb in at night so I didn't have to go traipsing around in the dark to feed her, and when she was taken the ewe began calling for her. After a week we were able to put all three back out into the pastures. The ewe now loves her two lambs, although she doesn't feed the rejected one, and the whole flock is fascinated by the process of bottle feeding.
So it all turned out ok for us, but it doesn't solve your problem. No, you can't put him outside at night yet at the mercy of foxes and the ewes, so the cattle trailer it has to be. Were you to pen him as we did with his mum and twin, then the other sheep would be on her own which isn't good welfare.
My suggestion is that you take him into the field to feed him and play with him, which will attract the twin to watch too so at the very least they will each have a playmate. As the post lambing time becomes more distant and the lamb is less newborn looking, the ewes will hopefully relax and stop shoving the lamb, and eventually he will be accepted and can live outside.
btw has he been ringed? If you want to keep him he will need to be castrated, and it has to be done in the first 7 days, so maybe take him back to the person who helped with the birth for ringing.
As it was your father who organised the tupping then he must accept that the lamb needs care and safety so has to remain in the trailer for a while until he is accepted as part of your mini flock
Good luck