Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/4=88
M:4/4
K:G
['GB/c<dc/ BGc/B/A/B/ GB/ c<dc/', 'de d2 cdBG']  
X:1
L:1/8
Q:1/4=88
M:4/4
K:G
 GB/c<dc/ BGc/B/A/B/ | GB/ c<dc/ BG A2 | GB/c<dc/ BGc/B/A/B/ | GB/ c<dc/ BG A2 |: GB/c<dc/ de d2 | 
 cdBG A/G/A/B/c/B/A/B/ | GB/ c<dc/ de d2 | cdBG A/G/A/B/ G2 :|  