Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:Bmin
['B,DF B3 DFB']  
X:1
L:1/8
M:6/8
K:Bmin
|:"Bm" B,DF B3 | DFB d3 |"^(D)" fdf"A" ece |"Bm" dBd"F#7" c^AF |"Bm" B,DF B3 | DFB d3"^I" | 
"^(F)" fed"F#7" cB^A |"Bm" BFD B,3 ::"D" DFA d3 |"Bm" FBd f3 |"D" FGA AGF |"Em" EFD"A7" CB,A, | 
"D" DFA d3 |"F#" F^Ac f3 |"Bm" dBd"F#7" cB^A |"Bm" BFD B,3 :|  