Hermione’s relationship with her own parents is one of the more curious things in the series. She seems to spend less and less time with her parents, and by the summer between sixth and seventh year, is falls into classical magical thinking. Her decision to remove her parents memories of having a child without consulting them, however well intentioned, is condescending and paternalistic - an attitude wholly inappropriate for a daughter/parent relationship. Like the incident with the firebolt, her conclusions and thus actions might in the end be the right ones,1 but her reasoning is all wrong.
Frankly, as a parent, this is the section that utterly horrifies me. By fourth year, as a fifteen year old girl, Hermione has essentially divorced herself from her parents. If one of my children were to do that, I would be devastated. I understand that one of the nearly universal fatal flaws of having children as protagonists in literature is the impossibility of portraying adults reasonably, but consider this as one of Hermione’s parents. Assume, for the same of having a series, that Harry’s participation in the war is in fact necessary. Given that, one can, somewhat reluctantly accept, that the support Hermione gives him at school is also critical. As a parent, I would rage against the dysfunction that has allowed Harry’s situation to occur, but I can accept that it would eventually escalate world wide if not stopped. When you cannot flee, you have to stand and fight.
Hermione does not give her parents this chance. Starting at age twelve she starts censoring all the important details of what happens at school. That is totally unacceptable. No reasonable parent would accept that behaviour. As a consequence of this, she feels less and less connected to them. A reasonable parent would notice this, and recognise something is wrong. We are left to assume that Hermione’s parents are so wrapped up in their careers that she can be absent from home all but a (maybe) a few weeks between her fourth and fifth year, and they notice so little that they neither demand she come home for Christmas break, nor that she stay with them the summer after fifth year.
Speaking of which, if Hermione is not explaining things to them, how does she end up with the Order all summer? It cannot be “for safety” - her parents have not been told she is in danger. Again we are seeing a portrayal of Hermione’s parents as essentially neglectful to the point of criminal negligence. Our daughter is off with we do not really know who for the entire summer with no way to contact her. Oh, and we have not seen her since early August last year, where we did not talk enough to know anything of significance about her incredibly stressful school year.
Then, to cap this pattern, she unilaterally modifies their memories to erase her own existence, and sends them off to Australia. Do you really think this seventeen year old girl with no practical experience in the non-magical world took adequate care of wrapping up all the loose ends such a move would have in her parents lives? This is a really big question if she planned on the move being essentially permanent, but it is an impossible one if she planned on them being able to return should the war ever end successfully. What did she do with their house, their business, the clientele that business' success is based on? Is there any extended family or even close friends with whom she is causing her parents to cut off all contact essentially overnight and without explanation?
And it would have to be without explanation. How could it be otherwise? Her parents do not even know their own names. Having a new identity, they cannot be responsible for mothballing the dental practice, contacting friends or family, or any of the dozens of details that would need to happen if they are to go overseas in a way they can hope to return from.
I am unsure how necessary it was to modify give them a new identity this way. I agree they did probably need to either go into hiding or leave the country (at least temporarily). If I “woke up” from this however, was de-enchanted to find myself in Australia having had no say in going, I would be massively upset. The person who caused this would have to admit to having been wrong to do so to repair that relationship. If they do not, how can I trust them?