Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:6/8
K:Bbmin
['D/E/ FDE FDE', 'B2 c/c/ dcB']  
X:1
L:1/8
M:6/8
K:Bbmin
 D/E/ | FDE FDE | FBA F2 D/E/ | FBF EDC | B,3- B,2 D/E/ | FDE FDE | FBF E2 D/E/ | FBF EDC | 
 B,3- B,2 || D/E/ | FBc dcB | ABc B2 c/c/ | dcB ABc | B3- B2 c/c/ | dcB AGF | EDC B,2 D/E/ | 
 FDC/B,/ A,CD | B,3- B,2 ||  