Before the story of Tzelophchad’s daughters is even told, their names are listed, in Numbers 26:33. The list appears again, in 27:1, before they ask their question to Moses about their inheritance, and a third time, in 36:11, in conjunction with the law requiring them to marry within their tribe. The laws related to their situation would have been just as clear without listing their names; why bother repeating them?
Even today, if parents have a run of three or more children of the same sex, they can expect some muttering and speculation, and possibly even rude questions, about whether or not they are disappointed, or “trying for” a child of the other sex, or some such. In a society as patriarchal as the ancient Middle East, one can imagine how much more gossip would surround a father with a prestigious ancestry who had five daughters and no sons.
Perhaps Tzelophchad and his wife were trying to quench that gossip when they named their youngest daughter Tirtzah—from the root r-tz-h, “to be pleased with, to accept.” (See, for example, Genesis 33:10, Exodus 28:38, Leviticus 26:41.) Tirtzah and her sisters could observe that if the youngest child of the family was given this name, then kal va-chomer the four elder daughters were valued for who they were, and their parents had no regrets that God had only sent them daughters. With that self-confidence, they were able to present their case to Moses.
The lesson for contemporary parents is left as an exercise for the reader.