Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/4
Q:1/2=84
M:4/4
K:F
['B A G']  
X:1
L:1/4
Q:1/2=84
M:4/4
K:F
 (F/G/) | A B c d | c B A G | A B c d | c2 A"^," c | d d f d | c B A"^," c | B A G F | c2 A c | 
 B A G F | G/F/E/D/ C"^," F | B A G F | G2 F"^," c | B A G F | G/F/E/D/ C"^," F | B A G F | 
 G2 F z |]  