Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:D
['a ||S fd d2', 'F2 Eeed e2 eg fd d2 AF', 'fdad bdad']  
X:1
L:1/8
M:4/4
K:D
 a ||S fd d2 AF F2 | Eeed e2 eg | fd d2 AF F2 | Dddc d2 d :| g | fdad bdad | Beed e2 eg | 
 fdad bdad | Addc d2 dg | fdad bdad | Beed e2 eg | fadf gbag | fedc dbag!D.S.! ||  