Create a composition by utilizing the given alphabet-based musical pattern and the provided melodic theme.
X:1
L:1/8
Q:1/8=120
M:4/4
K:G
['FGA B3 A BedB', 'z def g3 f fedB']  
X:1
L:1/8
Q:1/8=120
M:4/4
K:G
"^moderate" FGA | B3 A BedB | AG E2 z GBc | d3 e dBGB | A4 z FGA | B3 A BedB | AGED EFGA | 
 B3 c BAGA | G4 z || def | g3 f fedB | dB G2 z def | g3 f fedB | A4 z ddd | b3 a ageg | 
 dB G2 z FGA | BedB AGEF | G4- G4 |]  