Craft a musical piece that integrates the provided melodic theme and the corresponding alphabetical pattern.
X:1
L:1/4
M:6/4
K:Bb
['A G', 'c d']  
X:1
L:1/4
M:6/4
K:Bb
 F | B3/2 c/ B B A G | A G F B2 D | E F G F3/2 G/ F | F (B2 B2) :| F | B2 c d c d | e d c d2 c | 
 B2 c d c d | e d c d2 c | B d d A c c | A G F B2 D | E F G F3/2 G/ F | F (B2 B2) ||  