Read what the recipient will see
A handoff only needs “Please cover the 4:30 collection.” An explanation copied from a private message can be removed. Also check the source material and permissions so the same detail does not return in the next draft. Check the title, summary, attachments and source labels as well as the main text. A clean sentence can still point to a source whose title reveals a private detail.
Rewrite the minimum shared action
A workable pickup note states who is needed, where, when and whether they have agreed. Leave the reason for the original adult's absence in their private record. Read the proposed handoff without relying on that private context. If it is still clear and useful, the extra detail was unnecessary.
Prevent the same leak
Check which source records were supplied to the assistant and whether it was working for an individual or the shared household. Correct the input scope if needed, then try a fictional example. An instruction asking the model to be discreet is useful guidance; it does not enforce account access controls.