Robynne, I would certainly agree that it is wrong - VERY wrong - if someone decided to open a WikiTree account for a family member or an acquaintance, without the knowledge or approval of the acquaintance. This case, however, is very different. Kim and her sister are obviously taking many actions on behalf of their parents, who are not competent, and I am sure that they are legally entitled to be doing so. Opening WikiTree accounts for them would fall into the same category.
Perhaps, just to cover all bases, Kim could write to email@example.com and ask if they have any objection to her doing this.