Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:D
['D2 (3FED A2', 'e2 cA BG e2']  
X:1
L:1/8
M:4/4
K:D
 D2 (3FED A2 FA | ABcA dBcA | D2 (3FED A2 AB | cAGE ED D2 | D2 FD ADFA | ABcA dBcA | 
 D2 (3FED A2 AB | cAGE ED D2 :| f2 df fddf | e2 cA BG e2 | ff/f/ de fd d>d | cABG ED/E/ D2 | 
 fddf f2 df | e2 cA BG e2 | Addc defg | a2 ge ed d2 :|  