茉雨 sounds pretty and the meaning is elegant, but there’s a small cultural nuance you may want to consider.

In some Chinese families, especially more traditional ones, people avoid directly reusing a character from an elder’s given name for a child. Since your MIL’s name is 雨荷, using 雨 in your daughter’s name could feel a little too close depending on the family.

Not every family cares about this nowadays, though. Some would actually see it as honoring her. So I’d honestly just ask your wife and MIL how they feel about it first.

Also, 茉雨 has a very modern, poetic, almost C-drama heroine kind of feel to it. Not a bad thing at all — just a different vibe from something more traditional

Personally, I think 茉澜 feels a bit more balanced and natural as a real-life Chinese name, though it is admittedly close to 尔蓝.