>>87687500THE KITS
Aging them up to teens would do a lot for the show. You can still have them the youngest of the group and you can still have them be siblings, you can still have them be their "own" unit. But it would make them handier in fights, and if we're going by the "slowly rebuilds the empire to fight back against Mum-Ra" idea for the show then it would explain why they don't leave the kits behind in the Nu-capital when they go off on adventures and raids.
Lion-O being the little brother used to following his big brother's lead would help him connect to Wilykit being the little sister that usually follows her big brother's lead. We could also expand on the "spiritual" side of Wilykit they touched on with her music and the elephant guys.
They're both dreamers. Wilykit with magic and Lion-O with technology. Maybe she could almost be Lion-O's Jagga figure, or she could channel his spirit and the spirit of the Sword of Omens so Lion-O can communicate to them?
Maybe she could even learn some low-level magic skills? Stuff like causing smoke and illusions to compliment her and her brother's trickster theme?
How far should we take Wilykit being Lion-O's "high priestess"? Should it be full on Lion-Jesus and Mary Magdelene?