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
['DED AFA', 'dfd edc']  
X:1
L:1/8
M:6/8
K:D
 DED AFA | BGB AFD | DED AFA | B2 c d3 | DED AFA | BGB AFA | dfd edc | B2 c d3 :| dfd edc | 
 dcB AFA | dfd edc | B2 c d3 | dfd edc | dcB AFD | DED AFA | B2 c d3 | dfd edc | dcB AFA | 
 dfd edc | B2 c d2 f | afd edc | dcB AFD | DED AFA | B2 c d3 |]  