Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:6/8
K:Dmin
['d2 A B2 A']  
X:1
L:1/8
M:6/8
K:Dmin
"Dm" DFA"Dm/A" d2 A |"Dm" DFA"Bb" B2 A |"Dm" DFA"Dm/F" dfe | dBA"C" GFE |"Dm" DFA"Dm/A" d2 A | 
"Dm" DFA"Bb" B2 A | dBc"Dm" AGF |"A" ED^C"Dm" D3 ::"Dm" ada"C" gcg |"Bb" fBf"Am" eAe | 
"Dm" dcd"C" efg |"Dm" agf"Am" e3 |"Gm" dGd"F" cFc |"Bbdim" B_EB"Dm" ADA |"Bb" dBc"Dm" AGF | 
"A" ED^C"Dm" D3 :|  