Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/4=60
M:3/4
K:D
['', 'B2 dc', 'AB/c/ d2 df ec d4 c>d B2', 'cd>c BA GF ED C/B,/C/D/ E3 D']  
X:1
L:1/8
Q:1/4=60
M:3/4
K:D
"^slow" F/A/B/c/ || d2 gf ed | d4 d>c | B2 dc BA | B2 Bc d>c | BA GF ED | C/B,/C/D/ E3 D | D6 | 
 D3 GFE | D3 EF>^G | A3 Ad>c | B2 dc B^A | B4 GF/E/ | D>E F>G AB/c/ | d2 d>f e>d | c2 B3 A | 
 A4 AB/c/ || d2 df ec | d4 c>d | B2 dc BA | B3 cd>c || BA GF ED | C/B,/C/D/ E3 D | D6- | D6 |]  