Helpmates with twin by moving black king 10

a) 1.Rc3 Bd5 2.Bf4 d4#
b) 1.Bf4 Rd5 2.Rc3 Sd4#

JL:
Reciprocal change of black moves, white moves in the same time to the same squares. Everything motivated by need to open and close necessary lines.

a) 1.Bg4 (Bd4?) Bd3 2.Rg2 Be3#
b) 1.Rf5 (Rf4?) Bc5 2.Bg4 Bb5#

JL:
Anticipatory line closings by black. Rather too much of inactive material in respective phases.

a) 1.Sc2 Se6 2.Bf5 Bc6#
b) 1.Rf5 Bc6 2.Rc4 Se6#

JL:
Reverse of white moves that are mutual unpins. Also rest of strategy is well unified although rather simple due to not very strong white material.

a)
1.Sb6 Qc3 2.e2 Sd6#
1.Bc6 Qe7 2.Kf5 Sh6#

b)
1.Sg6 Qh2 2.Bg4 Sg5#
1.Sb2 Qc2 2.Rg3 Se5#

JL:
Rather well unified solutions although no deep strategy. 4 model mates.

a) 1.Bb7 a8S 2.Ka6 Sc7#

b) 1.Bd5 a8B 2.Bb3 Bc6#

c) 1.Bg2 a8R 2.Kf3 Rxa3#

d) 1.Bh1 a8Q 2.Kf1 Qxh1#

JL:
Obvious (?) AUW in synthesis with moves of black bishop on diagonal. Simple but well constructed.

a) 1.Rh3 Rg3 2.Rh4 Sxf6#

b) 1.Rg3 Rf3 2.Rg7 Rxf6#

c) 1.Rf3 Re3 2.Rf2 Sg3#

d) 1.Re3 Rd3 2.Re1 Rxd2#

e) 1.Rd3 Rc3 2.Rxd6 Sxf6#

f) 1.Rc3 Rb3 2.Rc6 Rxb4#

JL:
Maximal sixfold setting of Loshinskij theme (known also as "magnet"). Not very economical, though.

a) 1.Ba7! Bxe5 2.Kc5 Bf6 3.Kd6 Bd8 4.Ke5 Bc7#

b) 1.Qe2! Bxe5 2.Ke3 Bf6 3.Kf4 Bh4 4.Ke5 Bg3#

JL:
Motivation for the capture is clear - there is no other way to let black king to e5. Note nice choosing of 1st black move.

a) 1...Kg7 2.Kd7 Kf6 3.Sb4 Ke5 4.Sa5 Kd4 5.Kc6 Kc3 6.Kb5 Kb2 7.Ka4 Sc3#
b) 1...Kf7 2.Ke4 Ke6 3.Ke3 Kd5 4.Kd2 Kc4 5.Kd1 Kc3 6.Se1 Kb2 7.Sd2 Sc3#

Submitted by author as a simple demonstration of longer helpmate with "our" twin. Ideal mates, echo.