Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
Q:1/8=160
M:6/8
K:G
['G3 g2 e dBG AGE DEG BAG', 'e^de gfg', 'g gdB']  
X:1
L:1/8
Q:1/8=160
M:6/8
K:G
 (3D/E/F/ | G3 g2 e | dBG AGE | DEG BAG | BAA A2 B/A/ |"^5" G3 g2 e | dBG AGE | DEG BAG | AGF G2 :| 
 d |"^9" e^de gfg | e^de gfg | e^de gfg | fdB B2 d |"^13" e^de gfg | agf gfe | BcB AGA | BGE E2 :| 
"^17" (3D/E/F/ | G2 g gdB | G2 g gdB | DFA cBA | BFA GFE |"^21" D2 g gdB | G2 g gdB | BcB AGA | 
 BGE E2 :|  