I don't do dolls anymore, but I needed something like that I would google for it. A few years back there were dolls stores every where that carried things like that but when the collecting fad stopped the stores closed. I found this list that might help you. The Premiere new born baby doll kits might help.

https://duckduckgo.com/?q=hair+for+new+born+baby+doll&ia=products

I do dollhouse dolls, and use a fine hair called viscose. It's available from minikitz.com http://www.minikitz.com/ZenStore/index.php?main_page=index&cPath=165_168

There are (currently) three items on the page; I think you want either the second (shiny viscose) or third (matte viscose). Although she's talking about mini dolls in her description, I think one hank would be enough to wig several mini dolls, or to wispily wig a much larger doll. If you're worried about having enough, order extra.

I don't get anything for referring you to minikitz, but have purchased from Debbie for more than 15 years and have always gotten excellent and friendly service. She's also got lots more fun stuff on her site.

Don't know if this will help but I am not above buying a wig. [second hand] I clean it well and cut it apart for whatever use I need it for. Or what about a beauty supply store if you have one around you? They sell hanks of hair, maybe that would be an option! Good luck!!--Rosie

You can find a company that makes wigs for each client.

Also natural russian hair is very soft and well-combed.

Its the sample of full lace wig:

I use mohair. You can find it on eBay or Etsy.

I know this question was from a few years ago but I just came across it. There is a craft supply website that still carries some doll making supplies and has some hair that might work for you. Doll Hair at BJ's Craft Supplies