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 ask a sibling to share caregiving duties, use this factual base: record the care task, health instruction, schedule, cost, decision authority, and current risk.
Reduce the work of responding
Offer simple options, a narrow question, or a clear update that can be understood without another conversation. Assign one decision or task at a time and confirm who will do it, by when, and with what information. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Respect the boundary already visible
Do not remove the cared-for person's voice, shame a relative, or promise care you cannot sustain. Use clinicians, safeguarding, emergency services, or legal advice for neglect, abuse, incapacity, or immediate danger. A block, explicit refusal, legal restriction, or safety plan takes priority over the desire to explain more.