hdtr-Y ~ US

Yarn over hook 3 times, insert hook into next stitch, yarn over and draw up a loop. (5 loops on hook).

(Yarn over hook and draw through 2 loops) twice, yarn over hook and draw through remaining 3 loops.  (1 loop remains on hook).

ch2,  then push the hook through the half double treble stitch you’ve just made just above the bottom wrap (marked blue on the picture above),

yarn over and pull through loop (3 loops on hook), yarn over and pull through 2 loops, yarn over and pull through remaining 2 loops.  (1 loop on hook) .