Craft a composition that integrates the assigned alphabet-related musical pattern and the provided melodic theme.
X:1
L:1/4
M:none
K:D
['A G']  
X:1
L:1/4
M:none
K:D
 D | D D A2 A | =c2 c =F2 z G | A _B2 A A | G A2 z B | =c B A G B | A2 A D2 A =c2 B/A/ B2 z A | 
 G E =F G | E E D2 z |]  