<-- majored in Chinese history, studied Mandarin for 5 years.
Dede is not little brother, that's Didi.
Gege (pronounced like gerh gerh) = older brother
Didi (dee-dee) = younger brother
Jiejie (jee-air jee-air but said very fast so the r is almost unspoken) = older sister
Meimei (may-may) = younger sister
Some tips for chinese pronunciation:
The romanization of Chinese is called pinyin. So first and foremost, if you want help with pronouncing it, you can look up "how to pronounce pinyin". Here's a good pronunciation chart that covers every possible syllable and tone:
https://chinese.yabla.com/chinese-pinyin-chart.php . It's my favorite one but there are plenty of others.
Some tips: consonants are usually pronounced how you would think (yan is yan, wang is wang, etc) but there are a few that western speakers tend not to know.
Zh is not "zh" like the sound in mirage. It's a hard j sound, like in jerk. So zhong sounds more like jong than zong.
C is not a k or s sound, it's like a ts sound. Like saying "its". So cang is tsah-ng.
Z is a hard z, like how we say the z in pizza. We put almost a d in it, do you hear it? pee-dza. That's the z in mandarin. So zou is more like dzou.
X is a very sharp "sh." Like in sheep. Say sheep and feel how the air almost whistled as you say sh. That's x in pinyin. So xin is shin, like on a leg.
Q is a very sharp "ch" like in cheap. Again, similar to x and sheep. When you say cheap the ch is very sharp and whistle-y. So qin is NOT like "chin", with a more rounded out ch sound. Say chin but with the ch sound in cheap. Hopefully that makes sense and you can hear the difference.
And again, you can refer to the pinyin chart above to hear these sounds.
The other problem with romanization is that without tones and especially without seeing the character, a single chinese word could mean several different things. Like you translated "huang" as bright but it could also mean yellow, emperor, wilderness, lie, panicked, locust.... you get the gist. So on one hand you could just throw up your hands and not care about meaning, or you can put the actual meanings in the footnotes if that's important to you.
Also as you may have noticed reading Chinese novels, in ancient china people often had several different names, and nicknames were not given like we give, where we simply shorten the sound or add an "ee" at the end. Like Jennifer becoming "Jen" or James becoming "Jamie." So if you name your characters with Chinese names, you cannot simply have them be called "Meimei" or "Taitai." You either have to also find their "nicknames" (usually a single word different from any in their common name, like how in MDZS Jiang *Wanyin* is called Jiang *Cheng*) or always refer to them as their full names.
People VERY close to someone will simply take the last word of their name and add "ah" to it. So Li Jiao Mei could be called "A-Mei" by family. Pretty much only family once you're an adult. It's kind of patronizing for even your closest friend to call you that beyond the age of like 8 or so, but older family members kind of get a pass cause they've known you since you were a baby of course.
Speaking of family, family names are EXTREMELY important in China, and of course they are passed down from the father's side (most of the time, there are a few exceptions because china is so big and diverse but like 99% of the time, it's patriarchal). So a ruler having "Wang" as their last name would be preeeetty unlikely unless their family has been the ruling family for generations going back to the time before people even had last names.
This also frees you up to not worry about the meaning of last names. The meaning doesn't matter as much as the connection and familial ties that come with the name and I don't know many people who would decide on their baby's name based on how it works with the meaning of the last name. So the last name does not have to have a meaning related to the other two words.
Okay sorry I wrote you an entire novel aha. I'm happy to answer any other questions you have.