1–
: 1M+2M ½ Fig8 round the W ; 1W+2M ½ Fig8 down (1c is on M side, 2c on W side, the W on 1diag)
9–
: 1W+2W progressive BtoB ; set | cast cclw  **while**{4}    1M+2M set | cast clw ; Progressive BtoB (all have now changed sides)
17–
: Turn opposite BH ½ | Circle4 L ½ ; ½ R&L, end in promhold with P, facing across (1c is on W side, 2c on M side)
25–
: All advance to midline, M Lsh to Lsh, and continue with Tournée (2,1)

{{explanation}}
Progressive Back to Back: pass Rsh, and pivot L ½ | Retire into exchanged places