Thanks for sharing your patterns with the rest of the world!
My husband is in the throes of knitting your argyle cardigan pattern for a friend's baby, and we are both stumped on exactly where the decreases should be made on the sleeves as neither of us have knitted this way before. It seems logical to me that they should happen at the underarm - could you please tell me if this is right?
Firstly, you're quite welcome, I always get really excited whenever someone does one my my patterns! I hope you'll be making pictures available? I'd love to see it when your husband is finished!
Secondly, as per the instructions, the rounds for the sleeves should begin and end at the bottom of the armscye (a.k.a the armhole). Since the decreases (again according to the instructions) are done at the beginning and end of rounds, yes, you're quite right, the decreases occur at the underarm. (At least, this is true at the beginning of the sleeve. As the sleeve gets longer and longer, you get farther and farther away from the underarm, so saying that the decreases are always at the armpit eventually becomes inaccurate...but yes, I know what you mean, and you're right.)
The schematic diagram also demonstrates this, I'll show you how. This is the schematic:
If you rotate it sideways, which is how the garment will be positioned when a sleeve is being worked (I've put the arrow in there to show the direction you're knitting in), you can see more easily where the decreases happen:
Specifically, they happen where the sleeve is angling and becoming smaller, and that point is right at the bottom of the sleeve (that is, the bottom of the sleeve when the cardigan is being worn).
I hope this makes things more clear for your husband! Please let me know if you have any other questions.