Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:3/8=110
M:6/8
K:Bb
['dBb a2 g Tf3 gfe dcB', 'B3 c2 f e2 d c2 B']  
X:1
L:1/8
Q:3/8=110
M:6/8
K:Bb
 B2 f dBb | a2 g Tf3 | gfe dcB | A2 B A/B/cF | B2 e dBb | a2 g Tf3 | gfe dcB | c3 B3 :: c2 f e2 d | 
 c2 B AGF | f2 b a2 g | f2 e dcB | e g2 d f2 | c e2 dcB | g3 fab | c3 B3 :|  