Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/8=300
M:6/8
K:G
['', 'cde dBG', 'G GBd efg fdd def gbg afd']  
X:1
L:1/8
Q:1/8=300
M:6/8
K:G
 G |: GBd gfg | edc BAG | GBd efg | fdd d2 f | gbg afd | cde dBG | GAB cAd |1 BGG G2 G :|2 
 BGG G2 c |: BGB cde | dBG A2 G | GBd efg | fdd def | gbg afd | cde dBG | GAB cAd |1 BGG G2 c :|2 
 BGG G2 |]  