Create a musical composition adhering to the provided thematic and alphabetical guidelines.
X:1
L:1/8
Q:1/2=100
M:2/4
K:Bb
['BcBF dBfd', 'B2 gecg fdBf edcB AcAF BFdB fdbd']  
X:1
L:1/8
Q:1/2=100
M:2/4
K:Bb
 BcBF | dBfd | gecB | AcAF | BcBF | dBfd | gecA | B2 B2 :: gecg | fdBf | edcB | AcAF | BFdB | 
 fdbd | ceAe | B2 B2 :|  