What should I do if I have a family member with a history of high blood pressure who suddenly wakes up at night, is forced to sit up, is irritable, and coughs up pink phlegm?

If an elder in the family develops such a condition, they should be taken to the emergency room immediately for treatment.
Patients with these symptoms are at high risk of developing hypertensive crisis or acute heart failure, which can be life-threatening.
While waiting for the ambulance to arrive, blood pressure can be measured immediately at home, oxygen can be administered if emergency medication is available, appropriate antihypertensive medication or heart failure medication can be given, the patient can be made to sit with legs down to reduce the amount of blood returned and the tension can be calmed.
The key is to get to the emergency room quickly and get specialist treatment from a doctor.