Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:2/4
K:D
['dd cd ef d2', 'A/A/ defg']  
X:1
L:1/8
M:2/4
K:D
 A | dd cd | ef d2 | a>b ag | fga A/A/ | dd cd | ef d2 | e>d ce | d2 !>!d :: A/A/ | defg | 
 (!>!af) d2 | e>d ef | gfe A/A/ | defg | (!>!af)d !>!d | !>!e>d ce | d2 !>!d :|  