Make the first sentence usable
Lead with the reason for writing so the recipient does not have to decode a long emotional introduction. For a message about how to support a parent during a custody dispute, use this factual base: acknowledge the event and practical strain using only information the parent has chosen to share.
Reduce the work of responding
Offer simple options, a narrow question, or a clear update that can be understood without another conversation. 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.
Respect the boundary already visible
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. A block, explicit refusal, legal restriction, or safety plan takes priority over the desire to explain more.