I'm underselling that a bit: she was also Lightning Lass and Lightning Lord's mom, too. From 2001, Legion Worlds #2, "You Are Here: Winath" Written by Dan Abnett and Andy Lanning, art by Enrique Breccia; and "A Change in Climate" Written by Dan Abnett, art by Darwyn Cooke.
After a disaster that left the United Planets' system of stargates in ruins, and eleven Legionnaires presumed dead, the team had broken up. Ayla Ranzz, formerly known as Spark, returns to her homeworld, the farming planet Winath. Her brother Live Wire (this version of the Legion forswore the usual naming conventions of Lasses, Lads, Boys, and Girls) was among the missing; which held more significance to Ayla even than losing a twin sibling usually would: on Winath, twin births were standard, a "solo" birth an oddity, and being alone virtually unimaginable. In fact, their brother Mekt had been a "solo," which was assumed to be why when they all received lightning powers, Mekt went on to become a supervillain. Which makes seeing Mekt at the family farm a surprise for Ayla: he had been released, with a power-dampening bracelet and mood-altering drugs.
Although she plans to return to a quiet life on the farm, a series of storms unplanned by planetary weather control make Ayla suspect Mekt. Investigating, she finds Mekt on a climate control station; but he had been investigating himself: a farming co-operative was using the storms to try to ruin their rivals and consolidate the farms. Stopping the conspirators causes a massive storm, that Ayla couldn't stop on her own, but with Mekt's help she manages.
Later, at Garth's funeral marker, Ayla gets a surprise from Mekt: the news just broke that the lost Legionnaires, including Garth, had returned. As Ayla runs to try and get a message to her twin, Mekt destroys the marker with a lightning bolt...
The back-up story, "A Change in Climate," is just as personal: Ayla, Garth, and Mekt's mom Dalya is in the middle of some spring cleaning, when she's visited by her twin, Lilya. Dalya was a bit worried, since with off-world travel now difficult, population expansion had created a housing shortage, and she was concerned that the government might decide to relocate citizens there. Finding a box with Ayla's jump rope, and Mekt's stuffed toy, sets her off, and Dalya wonders what she did wrong: a solo murderer, a dead hero twin, and a daughter that hadn't come home yet. Lilya assures her, she did fine: while Mekt was getting himself together, her other two did fine for themselves; unlike her own lazy brats...This may seem offbeat for a superhero team book, and I don't think it would work as well in another one. Can you imagine a visit with Beast's parents, or catching up with Carol Danver's folks? But through years of mentions and notes from Legion stories, Winath becomes almost a character itself. It's why Legion of Super-Heroes is so immersive for some, impenetrable for others.