Develop a musical composition using both the specified melodic theme and the alphabetical pattern naming.
X:1
L:1/8
M:3/4
K:G
['_BB A2']  
X:1
L:1/8
M:3/4
K:G
 GG A2 d2 | _BB A2 G2 | AA c2 _e2 | d6 | d2 d4 | _BB A2 FD | DF A2 _B2 | G6 |]  