What word would be used for as a gender-neutral offspring, for when the gender doesn't matter or is unknown, like "Your child," or "My children"?
how is ь in донька changing the pronunciation of н ? I don't know how the soft sign is supposed to sound since the situations with it always seem to have it.
No difference, дочка, донька - you can use any. Just mind the difference in stress: дочкА, дОнька (audio for this sentences has wrong pronunciation of донька)