Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:4/4
K:C
['AGA BGE', 'gdB cec dBG', 'GBd GBd']  
X:1
L:1/8
M:4/4
K:C
[M:6/8][K:G] e.g"^Copey's""^Cozy" .adad ve f"^Maid in the Meadow" .Pa a d3 eve d ee eaed[Q:1/8=160] .A/B/ | 
 c3 B3 | AGA BGE | DEF GBG | AGA BGE |"^5" cec BdB | AGA BGE | DEG AGA | BGF G2 :| d | 
"^9" gag gdB | cec dBG | g2 e gdB | ecA A2 f |"^13" g2 e gdB | cec dBG | DEG AGA | BGF G2 :| z | 
"^17" GBd GBd | Gce Gce | GBd GBd | ecA A2 B |"^21" GBd GBd | Ace e>fg | dcB AGA | BGF G2 :|  