Hi. I run a parents consultancy (we have sleep experts who we work with along with all our other expert consultants) but I also have a 20 month old son who started nursery recently and had a massive separation anxiety phase and essentially did what your son described above and my life became very difficult. I am working flat out on a new business, admittedly I didn't have a new born to deal with but I was struggling none the less. In the end, and it was about 5 weeks that I allowed it to go on for (because I was embarrassed to tell me people I was struggling seeing I run a consultancy dealing in this sort of thing!), I spoke to one of our consultants and her advice was until your child is happier in themselves during the day i.e, less clingy and needy then do whatever you need to do. So I decided to co-sleep with Gabe. This lasted for about 3 weeks and I thought that was it, we had moved in together. But I managed to get some sleep and feel better/stronger and I also felt that he was reassured and felt lots of love/security. Yes, I had a few kicks in the back but at least I slept. When I felt he was past the separation stage and was beginning to call my bluff a little and to be honest it was more about me feeling stronger , I got tough. With my partner's help, we started sleep training on the weekend. By the way, we didn't speak to him at all whilst we were doing it. We reassured him by touch but no words but every consultant has their own technique and whatever you choose, consistency is key. For the first three or four nights, he essentially was up all night, and I mean up all night! And so were we. But we persevered and took it in turns and one of us would wear ear plugs so we could get some rest. It was cracked in about a week and it was amazing to see the transformation in him. He eats more, he's stopped being clingy. He has energy. He is happy. He is sleeping and, we are, and it is such a relief. The other thing some of our experts have advised other parents is to try giving him no sugar before bed time. So no desert with dinner or fruit. I would also start the bedtime routine wind down earlier so that you have a bit more time on your hands to settle him, this will allow you some evening back before no doubt doing a dream feed for your 14 weeks little girl. I wouldn't use white noise or any other sleep association things. He needs to learn to sleep on his own again and he will but if in the meantime, you need to co-sleep with him or your partner sleep in his room, or he has a mattress next to you, then I would just do it because my son is now not pointing to my room anymore, their memories are so small that it's almost he has forgotten that mummy and Gabe moved in together for a while. PS If you can afford it, I would also get a night nurse, even if it just for one or two nights. They can help with your little one but you can also get a night nurse who has experience with toddlers and they will help you a little with them too, only if you want it though. Good luck. I know you have more on your plate than me but you will get through this x