Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/8=120
M:2/4
K:G
['dB BA/G/ ce e2 dB c/B/A/G/ AG', 'BGG BG G2', 'Bd ce dB ce dg', 'gd eg dB ce dg', 'GA/B/ cB cd/e/ fd ec AG', 'eg ge']  
X:1
L:1/8
Q:1/8=120
M:2/4
K:G
"^A" dB BA/G/ | ce e2 | dB c/B/A/G/ | AG E>D | BA AG/A/ | B/A/B/c/ d>e | dg d/e/d/c/ | BGG || 
"^final" BG G2 |]"^B: \"1st and 3rd\"" G/A/ | Bd ce | dB ce | dg GB/d/ | BA AG/A/ | Bd ce | dB ce | 
 dg d/e/d/c/ | BGG || B/d/ | gd eg | dB ce | dg GB/d/ | BA AB/d/ | gd eg | dB ce | dg d/e/d/c/ | 
 BGG ||[K:C]"^C: \"2nd and 4th\"" G/F/ | EG GA/B/ | cB cd/e/ | fd ec | AG G>F | EG GA/B/ | 
 cB cd/e/ | fd ec | AG G || d | eg ge | dc df | eg ge | ad de | eg ge | dc/A/ cd/e/ | fd ec | 
 AG G2 ||  