Re: -Calling Your Relatives by Relations or Uncle/ Aunty
One of my khala’s 5 years older than me. So this one time when we went shopping in Pakistan, i guess i was like 10 yrs old… whenever i needed to ask her something i’d say ‘khala.. this n this n this.’
The moment we came home, my khala went: ‘Khabardaar agar tumne mujhe aayenda khala bola. Aaj se tum mujhe api bola karo, dekha tha kaisay log dekh rahay thay jab tum mujhe khala bula rahi thi? :(’
Eversince, i call her api and her husband bhai. 
But when it comes to other relations, I like to call them by relation. It makes ur bond more personal and I think it’s also a form of respect. 