Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:Bb
['Bcde fgfd fbfd fgfd e2 ge d2', 'B2 bBaB', 'egfe dcBd']  
X:1
L:1/8
M:2/2
K:Bb
 F2 | Bcde fgfd | fbfd fgfd | e2 ge d2 fd | cdcB AGFA | Bcde fgfd | fbfd fgfd | e2 ge d2 fd |1 
 cBAc B2 :|2 cBAc B3 || (f |: b2) ba bf B2 | bBaB (f/g/f) dB | egfe dcBd | cBAB c2 (3fga | 
 b2 ba bf B2 | bBaB (f/g/f) d2 | egfe dcBd |1 cBAc B2 (fa) :|2 cBAc B2 ||  