1–
: 1c+2c Adv{1}&Ret{1} | 1c cast as 2c dance up ; 1c turn LH to face 2cnr | turn 2cnr RH into promhold and face 3cnr
9–
: ½ Reel4 on 1diag, but at the end the cnrs turn LH ¾ to finish at 2cnr (across from their starting position) ; 1c turn LH to face 2cnr **while**{2} guiding their cnr RH to 1cnr | turn 2cnr (=3rd cnr person) RH into promhold and face 3cnr (all cnr persons have moved one place clw)
17–
: Repeat [9–16] with the new corners, but at the end 1c turn to own side (3x,1,2x)
25–
: Diag R&L (2,1,3)

{{explanation}}
On 3rd time through, new 3c+4c copy [1–4] to progress.  
Note: numbered cnrs refer to positions