Shang-Chi's familial relationships are a bit of a mess in the comics, and while "Shang-Chi and the Legend of the Ten Rings" makes it clear that the family continues to be unlikely to gather together for a nice Sunday dinner, the movie has understandably streamlined some of the more convoluted parts of the equation. For instance, the history of The Mandarin is extremely complex in the comics, even without the MCU's inclusion of the copycat Trevor Slattery (Ben Kingsley). It's also worth noting that in the comics, Shang-Chi's father isn't the Mandarin at all, but a sorcerer called Zheng Zu, aka Fu Manchu. As such, it's no surprise that the "Shang-Chi" movie opts to go with a fresh take on Shang-Chi's dad in Tony Leung's Wenwu, who carries the Mandarin mantle, but is essentially a brand new character.
The story of Xialing is somewhat similar, though the reason for the simplification is likely rather different. Though Meng'er Zhang's character doesn't seem to have a direct counterpart in the Marvel comics universe — at least yet — this may have something to do with the simple fact that the comics version of Shang-Chi has no less than five sisters. This, of course, is a ton of characters to introduce in a movie that's already tasked with a ton of world-building, so it's hardly a surprise that the powers that be opted to go with a single sister character that might carry some of the comic book versions' characteristics, but none of the potential plot baggage.
