On the Reboot Darkstar fusion, wouldn't Umbra/Tasmia be the source Legionnaire for that? and not Dawnstar?
Could be... honestly she doesn't resemble any Legion girl, so my assumption was based on the "Star" part of her name.
With the white streak in her head, maybe she's supposed to be Invisible Kid II ? She wouldn't be the only gender-bent character with a fusion, considering Shady is fused with Starhawk to create Shadowstar.
By the way, one of my first thoughts during the reboot part of the story was "I wonder which Legion Worlder will be tempted to use Kinetix's fusion in a fanfiction" :-)