Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/4=90
M:3/4
K:Bb
['D) FB (A3']  
X:1
L:1/8
Q:1/4=90
M:3/4
K:Bb
"Bb" (F3 B) cd | (B3 D) FB |"F7" (A3 c) GA |"Bb" G2 F4 |"Bb" (B3 d) BG | (F3 D) FB | 
"F" (A3 B)"C7" Gc |"F" (c2 F2-"F7" F2) |"Bb" (F3 B) cd | (B3 D) FB |"F7" (A3 e) GA |"Bb" G2 F4 | 
 (d3 f) ed |"Eb" (c3 G) AB |"Bb/F" (F3 d)"F7" cF |"Bb" B6 ||"Bb" (B3 d) cB |"Eb" (B2 e2) d2 | 
"C7" (c3 G) cd |"F" (c2 F2-"F7" F2) |"Bb" (f3 d) cB |"Eb" (G3 A) Bc |"Bb/F" (F3 d)"F7" cF | 
"Bb" B6 |]  