Purdah between non-mahram males and females

Q: My friend [24f] makes parda from her brother in law [17m]. However her father's first cousins is her husbands maternal uncles and she doesn't make parda from them. Upon telling her she brought the hadith of brother in law being death and said there is no specific ahadith relating to her having to making parda from her husbands mothers brothers therefore she doesn't have to. Is it true?

Heating the water for ghusl and performing fajr salaah in its time

Q: A person wakes up in need of a Fardh Ghusl 15 minutes before sunrise. There is no hot water and the person has chronic health issues. Using cold water will cause his health to deteriorate. It takes approximately 15 minutes to heat up sufficient water for Ghusl. If he waits, the time will expire and Fajr Salaah will become Qadha. What should be done in such a situation?