Can't read Japanese, but I think I know what's going on. Who/What _are_ Lala's parents, if any? We've seen Centorea's parents, Papi's parents, and Miia's mother.
Rachnera probably has like a bazillion sisters, if arachne reproduce like spiders, and her mother may have _eaten_ her father.
Suu probably can't even conceptualize what a "parent" is, since slimes seem like the type to asexually reproduce by splitting in half like amoebas.
And Meron's parents are probably back at her home in the ocean now that the latest chapter has shown that she is indeed, like we all speculated, royalty