Develop tuneful melodies adhering to the specified letter notation and including the supplied thematic aspect.
X:1
L:1/8
M:4/4
K:Amix
['dB B2 dBAF', 'DF F2']  
X:1
L:1/8
M:4/4
K:Amix
 dB | A3 B A2 de | f3 e dB B2 | dBAF ABAF | EGFE DB, B2 | FAAB A2 de |3 fga fe dB B2 | dBAF ABdf | 
 afeg fdde :| f2 df edBc | defd BAFE | DF F2 DF F2 | ABdf e d3 Bcd | fedf edBc | dcdA BAFB | 
 A3 B defa | afeg fdde :|  