a)

1. Sf2? Kg3 2. Sg4 Kh4 3. Kf4 Kh5 4. Bh7 Kh4 5. Kf5 Kh5 6. Sf3 (7. Bg6#)
5. ... Kg3!
5. Sf3+ Kh3? 6. Sf2#
5. ... Kh5 6. Kf5 (7. Bg6#)
1. ... Kxg1 2. Sg4 stalemate!

1. Kg5! Kg3 2. Bf5 Kh2 3. Sf2? Kg3 4. Se4+ Kh2 5. Sf3#
3. ... Kxg1 4. Sg4 Kf1!
3. Sf3+ Kg3 4. Shg1 Kf2 5. Kf4 Kf1 6. Bd3+ Kf2 7. Sh3#

b)

1. Kg5? illegal move!

1. Sf2! Kh5 2. Be2+? Kh4 3. Bg4 Kg3 4. Se4+ Kh4,Kh2 5. Sf3#
2. ... Kh6!
1. ... Kh5,Kg3 2. Sg4 Kh4 3. Kf4 Kh5 4. Bh7 Kh4 5. Sf3+ Kh5 6. Kf5 (7. Bg6#)

Keywords: miniature, twin, no white pawns, switchback (Kk,BSk), changed continuations, square vacation, line opening, line closing, selfblock, stalemate avoidance