Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
Q:1/4=90
M:6/8
K:Eb
['F2 G2 F E3- E'  
X:1
L:1/8
Q:1/4=90
M:6/8
K:Eb
 B |"Eb" B2 G"Ab" A2 c |"Eb" B3 G2"^(Bb7)" F |"^(Eb)" E2 D E2 G |"Bb" F3- FzB |"Eb" B2 G"Ab" A2 c | 
"Eb" B3 G2 E |"Fm" F2 A"Bb7" G2 F |"Eb" E3- E z || B |"Ab" c3- c2 c |"Eb" B3- B2 B | 
"Bb7" A2 G A2 B |"Eb" G3- (GA)B |"Ab" c3- c2 c |"Eb" B3- B2 G |"Fm" F2 A"Bb7" G2 F |"Eb" E3- E z |]  