Hermione's parents may have consented to their memory modification
So it occurred to me that the prevalent fandom belief that Hermione altered her parents' memories without their consent in Deathly Hallows is not from canon. Canon doesn't say anything about consent at all, in fact, which means it's possible they had a discussion and agreed to have their memories altered and go to Australia.
"I've also modified my parents' memories so that they're convinced they're really called Wendell and Monica Wilkins, and that their life's ambition is to move to Australia, which they have now done. That's to make it more difficult for Voldemort to track them down and interrogate them about me - or you, because unfortunately, I've told them quite a bit about you. "Assuming I survive our hunt for the Horcruxes, I'll find Mum and Dad and lift the enchantment. If I don't - well, I think I've cast a good enough charm to keep them safe and happy. Wendell and Monica WIlkins don't know that they've got a daughter, you see." DH p84
There's no indication in Hermione's explanation as to whether they consented. All we know from this is what she did to them, not whether they knew about it beforehand or agreed to let her do it.
I also found this next quote really interesting, given other Muggle-borns are apparently going into hiding. It makes it sound like these sort of discussions might be commonplace among Muggle-borns and their relatives, which could indicate it's more likely Hermione did discuss what to do with her parents. We really have no way to tell for sure.
"But hopefully it'll look like I've gone away with Mum and Dad; a lot of Muggle-borns are talking about going into hiding at the moment," said Hermione. DH p 86
Given how difficult it would be to just up and change names and move to Australia, it almost feels more likely to me that her parents consented and assisted with the transition. They have a successful dental practice, presumably friends and other relatives in addition to their work colleagues who would notice and still be calling them by their old names, a house and services they pay for, mail coming addressed to Granger, etc. We know their house still exists and they still own it even after they leave for Australia, because Hermione offers it as a potential safe house.
"I suppose we could try my parents' house, though I think there's a chance they might check there..." DH p136-137
Now that I think about it, I'm starting to believe all her parents' documentation--their passports, bank accounts, title on the house, etc.--are all still under the name Granger, but because of the enchantment, her parents THINK it all says Wilkins when they read it. Note that Hermione says, "I've also modified my parents' memories so that they're convinced they're really called Wendell and Monica Wilkins..." She doesn't say she changed their identities, but that she made them believe their names are different. This would mean the Grangers still exist on paper in the UK, also making it more likely for Voldemort's crew to assume they've simply fled with Hermione.
It being a charm that only affects their perceptions and beliefs also solves the issue of having to alter a whole life's worth of documentation in a short period of time; instead they'd only have to modify what they needed for Australia so they can be the Wilkins there. Given how ignorant wizards are about the Muggle world, it's possible they wouldn't need to change much at all, since there's probably little chance of a bunch of mostly pureblood DEs discovering the remaining paper trail that would lead them to Australia--and if they did manage to find it, everyone there knows them as the Wilkins anyway (I doubt it would be worth their time at that point to even go and search for them).
In any case, the prevalent belief that Hermione altered her parents' memories without consent is fanon, not canon. It's possible they didn't consent, of course (and I've written it that way many times before). It's just also possible they consented. Though, given the above, I'm leaning towards it being more likely they DID consent, or at least discussed what to do before she did it.
