Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/4=120
M:6/8
K:G
['D D2 G GFG ABA AGA BcB', 'G2 c B2 c ded ece d2']  
X:1
L:1/8
Q:1/4=120
M:6/8
K:G
 D | D2 G GFG | ABA AGA | BcB AGF | ABA AGE | G3 E2 D | DEF G2 :: c | B2 c ded | ece d2 c | 
 BGB def | gfe dcB | c2 a B2 g | ABA AGA | Bdg dBG | AGA BGE | G3 E2 D | DEF G2 :|  