Craft a piece of music that integrates both the suggested theme and letter-based structure.
X:1
L:1/8
M:4/4
K:Bb
['[DF]3/2 [DF]<[EG] [DF]/ [Fd]2 [DB]2 [Ec]3/2 [EB]<[EG]', '[DB]8 [Fd]2 [Fd]2 [Ff]3/2 [Fe]<[Fc] [EA]/ [DB]2']  
X:1
L:1/8
M:4/4
K:Bb
 [DF]3/2 [DF]<[EG] [DF]/ [Fd]2 [DB]2 | [Ec]3/2 [EB]<[EG] [FA]/ [GB]4 | 
 [FA]3/2 [FB]<[Fc] [FB]<[Fd] [Fc]<[Fe] [EA]/ | [DB]8 | [DF]3/2 [DF]<[EG] [DF]/ [Fd]2 [DB]2 | 
 [Ec]3/2 [EB]<[EG] [FA]/ [GB]4 | [FA]3/2 [FB]<[Fc] [FB]<[Fd] [Fc]<[Fe] [EA]/ | [DB]8 || 
"^Refrain" [Fd]2 [Fd]2 [Ff]3/2 [Fe]<[Fc] [EA]/ | [DB]2 [GB]2 [^Fd]4 | 
 G2 G2 [=Ec]3/2 [Ed]<[Ec] [EB]/ | [FA]2 [=EG]2 F4 [DF]3/2 [DF]<[EG] [DF]/ [Fd]2 [DB]2 | 
 [Ec]3/2 [EB]<[EG] [FA]/ [GB]4 | [FA]3/2 [FB]<[Fc] [FB]<[Fd] [Fc]<[Fe] [EA]/ | [DB]8 |]  