I agree that you need to keep any new budgie in quarantine for 30-45 days. Some of us who have had birds for some time, have seen disease spread. You never know if a new bird is harboring any illness, because birds mask illnesses until it’s more advanced. Once an illness is showing in a bird, depending on what it is, it may or may not be too late to reverse. Quarantine is very important.
Regarding Skyla with a new friend, it should not make her less tame or not want to be with you anymore. At least that is my personal experience with birds.
Btw, both are females. It’s not too early to tell. Budgies can be sexed very young if one knows what to look for.