Alright, my workday is finally finished, so here's my votes again, along with accompanying support.
[X] (Missy) Familiar (Zeus)
[X] (Laura) Iron Defender
[X] (Kayleigh) Guardian Beast of the Gear
[X] (Sarah) Overdrive
[X] (Lacey) Medical Mastery
-[X] (Lacey) Refund Strike Boost
Getting Missy, Laura, and Kayleigh their companion spells together works both mechanically (we have the required XP) and also within the story. Now that Sarah's joined the team, with another Guardian Beast in tow, why wouldn't the girls want to gain companions of their own.
Kayleigh is offered an immediate companion that is fully fleshed out, who can then be used to craft ammunition while we buy other spells for Kayleigh, as well as either assisting Tim to add another build slot or can work on it's own so we have two build slots for basic weaponry and tools. So more guns and gadgets for Kayleigh and anyone else interested.
With Laura and Missy, they are given the two companion spells that gain abilities over time, so getting them created now means we start the clock on gaining XP. With Missy, she can essentially "train" Zeus up rather than him having all the skills off the bat, and since we get to design all the aspects of Zeus's character, I was envisioning him presenting as more of a shy younger sibling who looks up to Missy, which is something she hasn't has a lot of in her life.
Laura is the most cautious of the girls when it comes to new things. She likes to delay things and ask questions and try to figure things out on her own. This makes suitable for the Iron Defender scenario, where a mage is poking at the Guardian Beast/Familiar ritual and accidentally casts it on a "smart" machine, bringing it to life. Also, since the Iron Defender is a creation of my mind, I want it to be given to the best possible candidate. Taylor and Sarah can't make Iron Defenders, Kayleigh really needs a Gear to thrive, and Missy has Zeus. So Best Ice Girl it is!!!
For Sarah, I was torn between my my logical brain and my emotional brain. On the one hand,
@Almech_Alfarion, while speed is great, flight will be paramount, especially since Cat Sith will gain it as well. In three weeks or less, Sarah will advance to a B-rank core and will be able to purchase Aerial Combat, likely costing 6 XP. So my logical side want to start banking XP for her immediately. However, my brain is also very liberal with the serotonin whenever we buy a spell and it reveals the hidden spell below it. So Overdrive is my compromise by both purchasing a spell and leaving an XP in the bank.
As for Lacey, getting Medical Mastery will Boost her two healing spells, improving her in the role we've put her in and that she has embraced. Refunding Strike Boost will give us another spell slot to work with, and remove a redundant spell since Olivia has that spell (along with Barret Boost) and Olivia has no reason to leave Lacey's side.
@Silently Watches, where is the list of spells that are available to learn? I can't vote for one if I don't know what I can vote for.
While Almech and Silently covered most of your question, one caveat is that Sarah is a template mage, so she can
only learn spells that are listed in her character profile on the front page.