Final answer:
A phlebotomist should always address the patient directly in a normal tone to seek consent, regardless of whether they are accompanied by a younger adult.
Step-by-step explanation:
When a phlebotomist is seeking consent from an older adult patient who is accompanied by a younger adult, the best course of action is to speak to the patient directly in a normal tone. It is important to always address the patient first and not presume that they cannot understand or do not have the capacity to consent. While parents can provide consent on behalf of their children, children are not competent to provide consent for older adults. Depending on the cognitive state of the older patient, consent may still be personally given or acknowledged through a legal guardian or healthcare proxy, but the initial interaction should be with the patient themselves with regard to their own healthcare decisions.