Thank you guys so much for the support! It really means a lot because a lot of people I know are a bit perplexed why I'd even bother.
A Sudden Introduction
On advice from my vets, they suggested that Lyta and Tally are ready to be in the same room. The girls have -loved- it. Lyta is normally an incredibly calm, gentle budgie but she's been clinging to the side of her cage to look at Tally. (And Tally's hanging upside down to look at Lyta. Because Tally isn't just a budgie, no. She's a monkeybird.) We've assembled perches so they can now sit as close to each other as possible.
Tally hasn't had any out of cage time since we moved her into that room a few days ago. We're pretty sure if we do, she'll go right to Lyta's cage and that could cause a problem. (We think it's especially important to introduce them on neutral ground).
Lyta, though. She surprised us. Usually when we take her out, she flies around the room once and then lands on her perch. And stays there for the next six hours. Not this time. She flew to Tally's cage where they talked and fell asleep after Lyta asserted dominance. It was adorable to see them both fluff up from the company.
It was tempting to move it ahead of schedule to let them meet officially today, but going to stick with the plan for this weekend: I want to make sure my partner is here in case something goes wrong. We need to keep watching to see if she throws any more tantrums. If she does, I'll put off the interaction a little while longer.
We're still in the process of trying to train Tally out of biting. She's managed to get us both really good, especially if she feels we aren't being fast enough with feeding her.
She loves being spoken to. If I lower my head to talk directly to her, she fluffs up. If, though, she sees a hand or fingers anywhere nearby, she attacks. We're still working on accustoming her to the idea that Hands Are Fun And Bring Treats.
I started conditioning her to the sound of the clicker, but she seems to feel threatened by it. So where Kosh literally got used to what a clicker meant in the matter of a few minutes and Lyta took maybe a couple of days, Tally's still boggled by it. We've tried using different clickers, but she doesn't like the sudden noises. All we can do, I think, is just be gentle with it and encouraging.
So, I expect we'll still be doing conditioning for a while yet.
One of the reasons we're considering letting Tally and Lyta meet is that Talia's tantrums have faded off. When we first got her, everything that happened that she didn't like would mean she'd attack the nearest object to her -- to the point where I was really worried she'd hurt herself.
Recently, though, that's calmed down heaps. She's pretty much stopped the angry attacking in the last week and, instead, does this furious little chitter. The chittering isn't happening as often as it was, so that's giving me a lot of hope here.
I think she's really starting to settle in here. Maybe one day, she'll even feel safe.