Craft a composition that integrates the assigned alphabet-related musical pattern and the provided melodic theme.
X:1
L:1/8
Q:1/2=80
M:4/4
K:D
['a2 fa g2 ef gfed cBAG FA', 'A2 FA B2 dB']  
X:1
L:1/8
Q:1/2=80
M:4/4
K:D
 a2 fa g2 ef | gfed cBAG | FA d2 GBeg | fedc d2 D2 :: A2 FA B2 dB | BAGF AGFE | A2 FA B2 dB | 
 AGFE D4 :|  