@Yenna thank you - excellent point with the video, he seems very comfortable holding the strings... I just checked the manual they sent me in the past and they quoted 32cm for each leg and 21cm for the arms, and I remember I added 1-2cm to that when restringing my Madalyn. What thickness you use for this? I normally go for the 5mm (legs) and 3.5cm (arms) but if you found out something thicker works better I'm all ears @Quinn.nnp - I see, so this was thanks to you they posted that video dressing Serein so nice of them to do that! I would expect them to add the strings, maybe even cut to the lenght - they normally add extra strings by default, even for stringed dolls, but definitely you can ask them as I always bought stringed dolls with them.
In my opinion, Souldoll's boxes and pillows are nice but not necessarily worth the extra shipping cost. If you don't need the box for storage and can string a doll yourself, I would order a doll unstrung. I would assume they give you string but you could contact them to make sure, their customer service has always been nice to me.