How to join sleeves to body in bottom-up sweaters
The tutorial below shows how to join sleeves and body together when working a seamless sweater from the bottom-up. This technique is used in my Mazzy sweater and is a technique used in every bottom-up seamless sweater (whether cardigan or pullover).
Tip: Once you have all the stitches on your body needle, the first few rows may feel uncomfortable as you knit over the sleeves. After a few rows of decreases it will feel more comfortable, but in the meantime, it can be helpful to pull up the cable as you knit across the sleeves as shown in the below photo: