This pattern is wonderful and very well thought out.
This yarn is super fun and super soft.

This sweater is much more beautiful than the picture shows.

It includes an innovative way to piece it together, neck band in the flat, so one doesn’t need a US 15 12.0 mm needle, 16” long. Not everyone is going to have that particular size, nor be able to get it just for the one purpose.

Made crew neck, 2 r 1x1 rib, bind off very loosely.

Size 2, 524 y
Entire back and ribbing only of front used 3 sk.
Main section of front and entire neck band used 2 1/4 sk.
Ea sleeve used 1 1/4 sk.

Elected to make shaped underarm area and shaped back neck, slightly shaped sleeve cap.
Worked sleeves cuff up, with gradual increases toward underarm area and sleeve cap.

This yarn:
Machine wash gentle, tumble dry gentle and everything will work out beautifully. Out of the machine, the sweater was size 100 and shaped all over the place. I thought it was ruined. Oh ye, have faith! Out of the dryer, it was perfect. Just a few fuzzies. I was amazed.

It shrank a little in length, but that was good because my daughter in law wants the sweater somewhat cropped.