Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/4
M:2/2
K:Ddor
['a _b a g f e d', 'd e f g a f e/d/']  
X:1
L:1/4
M:2/2
K:Ddor
 a | _b a g f | e d ^c d | e2 A a | _b a g f | e d c3/2 B/4c/4 | d3 :: d | e f g a | f e/d/ c d | 
 e2 A d | e f g a | f e/d/ ^c B/c/ | d3 :|  