Develop a musical piece that combines the given theme and letter-structured outline.
X:1
L:1/8
M:6/8
K:Dmix
['DdD cDd', 'AdA fed efe dBA']  
X:1
L:1/8
M:6/8
K:Dmix
 DdD cDd | DdD cAF | DdD cDd | fed cAF | DdD cDd | DdD cDd | fed cAF | DEF GAB ::[K:D] AdA fed | 
 AdA BAF | AdA fed | efe dBA | AdA fed | efe dBA | ABA FED | ABc dcd :|  