Develop a musical composition using both the specified melodic theme and the alphabetical pattern naming.
X:1
L:1/8
Q:1/2=100
M:4/4
K:Bb
['B2 bg f(dcB)', 'dBB c BGFE DFFD ECC=B cGGA BGFE']  
X:1
L:1/8
Q:1/2=100
M:4/4
K:Bb
 F | B2 bg f(dcB) | AFcF dFcF | B2 bg f(dcB) | FBAc dBB :: c | BGFE DFFD | ECC=B cGGA | BGFE DEFD | 
 B,BAc dB B :|  