Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/4=103
M:4/4
K:Bb
['FF F>G', 'F4 FF Bc d2 BB B3']  
X:1
L:1/8
Q:1/4=103
M:4/4
K:Bb
"Bb" FF F>G F2 D2 | BB"Eb" B>c B2 G2 |"Bb" FF F>G F2 D2 | DD"F" C=B, C4 |"Bb" DF F>G F2 D2 | 
 BB"Eb" B>c B2 G2 |"Bb" FF Bc d2 B2 |"Bb/F" cB"F7" d>c"Bb" B2 z || D |"Bb" FF F>G F3 F | 
"Eb" GB B>G"Bb" F4 | FF Bc d2 BB | dd"C7" c>B"F" c2 z D |"Bb" FF F>G F3 F |"Eb" GB B>G"Bb" F4 | 
 FF Bc d2 BB |"Bb/F" cB"F7" d>c"Bb" B3 z |]  