Relation between DaCapo III and the first two series I think all DaCapo series might have relation have relation between them . As far as I know from DaCapo I and DaCapo II,


In DaCapo II, Shirakawa Nanana is grandchild of Shirakawa Kotori from DaCapo I. 
Asakuar Junichi is grandfather of both Asakuar Otome and Asakura Yume. 


Are there any similar relations in DaCapo III and the previous series?
I've only watched the Da Capo III anime (which apparently only adapts the prologue of the original visual novel's story), but that features the characters


   Sakura Yoshino and Minatsu Amakase


from Da Capo II.