Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:D
['defd BcdB BAFA', 'd4 Bcde fB B2 def^g a2 gf']  
X:1
L:1/8
M:4/4
K:D
 defd BcdB | BAFA DAFB | ABde fg^ga | gAfA egfe | defd BcdB | BAFA DAFA | ABde fg^ga | gece d4 :| 
 Bcde fB B2 | def^g a2 gf | eA A2 eAce | gAfA egfe | defd BcdB | BAFA DAFB | ABde fg^ga | 
 gece d4 :|  