I saw a post commenting on how the headcanon of Lin as not knowing how to dance might not be correct, so I wanted to throw in my two yuans on the matter.
While I do agree that Lin is a more competent dancer than most give her credit for, I wouldn't take Suyin’s offer to be assistant director as evidence. Why? Do I need to remind you that this is the same Suyin who has been away from her sister's day to day life for the last thirty years, so how would Su know that (and the same Su who claimed to treat Kuvira like a daughter and we all know how that went). For all intents and purposes, Lin might actually be a good dancer or might've been as a child and teen, but Su still wouldn't know if that's true. I think she invited Lin because Suyin, ever the image conscious savvy one, it would be an excellent opportunity to showcase them working together in one of Su’s pet projects (Su's Cirque du Earth as one poster described it). And let’s not forget that Su would get to be on the lead role as dance director, so she can boss Lin around for a bit and continue her tradition of showing off Zaofu's virtues.
I still believe Lin can confidently manage herself on the dance floor, but it has nothing to do with Su, but rather with the Air Nomads. Part of the reasons Lin got along with Aang famously is that she expressed interest in learning about the Air Nomad culture. Not because it meant she would hang around with Tenzin, but because it meant spending time with Aang and Aang always found the way to make her laugh. She was also genuinely interested in their traditions because they were the polar opposite of earthbender culture, so one of the things she learned were Air Nomad dances, and she was quite good at them, even better than Tenzin. The agility she developed came handy in developing her earthbending later on. But this wasn't the only way she honed her dancing skills. Early on as a RCPD cadet and as daughter of Chief Toph Beifong, she was aware of the annual RCPD balls so not wanting to commit a faux-pass in a high-profile social event, she enrolled in the best dance school and learned classic and modern ballroom dances. The classes paid off, and over the years, she's been known to use her graceful waltz moves to negotiate increases to the police force's budget with council members on the dance floor and discreetly get tips from informants.
(ID:
Tenzin: "Today, we welcome our newest airbending master. I know our father would be so proud."
Image of Bumi with arrow tattoos, standing in front of the airbender crest ceremonial hall, mirroring how Jinora also had her ceremony as the music "Service and Sacrifice" plays. He's smiling with tears in his eyes, happy. )
lin has 100% fucked all three kataang siblings. both kya and bumi are aware of this, because they’re not totally oblivious, but poor tenzin still believes he’s the only one.
then, one day, tenzin suddenly has the epiphany during dinner (with his entire family around, including lin and both siblings), and has to try to stay calm while he realises what all the quips made by kya and bumi around him really meant.