Craft a musical piece that integrates the provided melodic theme and the corresponding alphabetical pattern.
X:1
L:1/8
Q:1/8=100
M:6/8
K:D
['bag fed f>ga']  
X:1
L:1/8
Q:1/8=100
M:6/8
K:D
 D3 F A2 | d>fe d2 A | B=cB B2 b | bag fed | f>ga afa | bag fed | f>ga bc'd' | d<gf e2 d | 
 fga afa | d'c'g fed | d'c'b afa | b<d'f e2 d :|  