Solution
1.+B1b 2.Kx1b 3.G*2b
1.+B1b 2.Kx1b 3.G*2b
1.R*1c
1.R3a+ 2.K1b 3.+R3b 4.P*2b 5.+B2c
1.S*3b 2.K3c 3.+B2b 4.Kx2b 5.G*2c
1.+R2b

R3b+

R3b+ threatens +R2a

N*2d

N*2d threatens G*1b
1.Gx2b 2.Kx2b 3.P*2c 4.K1b 5.+R3b
1.B3b+ 2.K1b 3.+B2a

B2c+

B2c+ threatens G*3b