Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:A
['A2 Ac', 'A2 fgaf e4']  
X:1
L:1/8
M:2/2
K:A
 A2 Ac E2 E2 | A2 Ac E4 | FGAB cdef | fedc cBAG | A2 Ac E2 E2 | A2 Ac E4 | efef fedc |1 cBAG A4 :|2 
 cBAG A3 :: A | fgaf e2 A2 | fgaf e4 | fgaf fedc | cBAG A2 Ee | fgaf e2 A2 | fgaf e4 | fgfa fedc | 
 cBAG A3 :|  