Develop a musical piece that combines the given theme and letter-structured outline.
X:1
L:1/8
M:6/8
K:D
['a2 a', 'ABd fed']  
X:1
L:1/8
M:6/8
K:D
|:"D" AFA AFA |"G" BGB BdB |"D" AFA Ade | fed"G" BdB |"D" AFA AFA |"G" BGB BdB |"D" def afe | 
 fed"G" BdB ::"D" def a2 a | baf afe | def a2 a | fed"G" BdB |"D" def a2 a | baf a2 a | 
"G" gag"D" faf |"G" edB BdB ::"D" A2 f fdf | fdf fed | A2 f fdf |"G" edB BdB |"D" A2 f fdf | 
 fdf f2 f |"G" gag"D" faf |"G" edB BdB ::"D" ABd fed |"G" ede"D" fed | ABd fed |"G" efe edB | 
"D" ABd fed |"G" ede"D" f2 f |"G" gag"D" faf |"G" edB BdB :|  