Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:D
['AFFF EFDE F2 AF BFAF E2 BE', 'fagf eAAA eAfA eAAA efge fddc dfag']  
X:1
L:1/8
M:2/2
K:D
 AFFF EFDE | F2 AF BFAF | E2 BE dEBE | ABde fedB | AFFF EFDE | F2 AF BFAF | E2 BE dEBE |1 
 ABde fddB :|2 ABde fddg || fddc dfag | fddd fagf | eAAA eAfA | eAAA efge | fddc dfag | fddc dfaf | 
 g2 gf gbag |1 faeg fddg :|  