Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:D
['F2 G', 'd2 e f2 f fag f2 e']  
X:1
L:1/8
M:6/8
K:D
|: F2 G A2 A | ABA A2 F | G2 A B2 B | BdB B2 A | F2 G A2 A | AdB A2 G | F2 G ABA | ABc d3 :: 
 d2 e f2 f | fag f2 e | d2 e f2 f | fag f2 e | d2 c B2 B | BdB B2 A | F2 G ABA | ABc d3 :|  