Write from facts rather than momentum
Pause long enough to remove accusations, assumptions, and details that belong to someone else. For a message about how to support a parent whose child is seriously ill, use this factual base: acknowledge the event and practical strain using only information the parent has chosen to share.
Offer a proportionate next step
Match the size of the request to the relationship and to what the recipient can reasonably decide now. Offer a meal, transport, childcare, advocacy, ordinary company, or another specific manageable help. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Protect privacy on both sides
Do not offer diagnoses, compare children, demand updates, or post about the family. Use medical, safeguarding, crisis, domestic abuse, or emergency services when a parent or child may be in danger. Use the most private legitimate channel available and do not share the exchange to recruit support or pressure.