You've got to get obsessed and stay obsessed

I think if you want her to be alive for her story put her in you story. I was struggling with this myself the other day. I wanted to write something set immediately after the war, but any way i cut it it was way more angsty than I wanted it to be because of Fred and because of the destruction of Andromeda's family. In the end Nat encouraged me to say fuck it. So now Fred and Tonks are alive and I am unrepentant. If I can do that to Fred and Tonks who are not even slightly ambiguous then you can definitely use Lavender.