Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:G
['G2 GF G2', '^cdgd B2 cB cdcA F2 GB cABG']  
X:1
L:1/8
M:4/4
K:G
|: D | G B2 d cBAF | G2 B2 D2 EF | GFGB cBAG | FAEA D2 dc | B2 BA G2 AB | cBcd e2 d2 | 
 BD (3BAB ADFA |1 G2 GF G2 B :|2 G2 GF G2 z |: A | Bc d2 ^cdgd | B2 cB cdcA | F2 GB cABG | 
 AF D2 D>D D2 | GFEc EG c2 | dBGD G B2 B | BA (3Bcd ADFA | G2 G F G3 :|  