I think it is only the Filipinos and the Chinese who use terms of endearment to address their older brothers and sisters. From the Chinese, the Pinoys got Kuya (koo-yuh) and Ate (ah-te) to call the eldest brother and sister, respectively. Diko and Ditse are used for second eldest male and female siblings, while Sangko and Sanse are for the third eldest brother and sister.
Let us not bother with the other terms but just concentrate on Kuya and Ate. Nowadays, Kuya and Ate are loosely used to address any older male and female regardless if he or she is a relation or not. My son calls the tricycle drivers, street vendors, security guards, school custodians and all older males as Kuya. My other four daughters do too. They call the canteen servers, cook, photocopy girls, and every other older female as Ate. When my kids were very young, there was a slight confusion on the household hierarchy for they call all our household helps as Ate while the house helpers addressed me as Ate too.
I really cannot recall when this practice of calling everyone kuya and ate evolved. When I was a kid back in the 60's, I called all unrelated older males and females as Ka as in Ka Juan and Ka Fely. Thus our laundrywoman was Ka Teresa and our neighbor with the gumamela bushes was Ka Choleng. Older brothers and sisters and cousins were entitled to be called kuya and ate. I was taught not to bother with diko, ditse and the likes. Too tedious.
The term Ka is synonymous with Mang for older males and Aling for older females. I called my parents' contemporaries as Ka or Kang (if there is some semblance of blood relations). I have one brother, yet my kids have titas (aunts) and titos (uncles) galore. No. I am not remotely related to this growing number of new relations. These relatives are family friends, their classmates' parents, their friends' parents, their friends' friends' parents, some of our neighbors, and what-have-you.
As their circle of kuyas, ates, titos and titas keep growing, so is mine. Every so often, I acquire a new niece or nephew. I am even an honorary "mommy" to some. I do not mind. Really. It seems like all Pinoys are related.
The use of Aling and Mang has evolved too. The youtube generation calls the elderly mommy and daddy or mama and papa or nanay and tatay.
I am now a grandma and by tradition my grandson should call me lola (grandmother). Ethan calls me "mom". I refuse to be a lola for the term epitomizes a sweet-gray-haired-elderly lady-knitting-while-sitting-on a rocking chair which I am totally is not. (I do knit, but not the rest of the description).
The other day, a street vendor passed by my house and asked me 'Nay, gusto ba nyo ng walis? (Mother, would you like to buy a broom?) Yep! That 40 something older male called me mother! I was so offended I replied Huwag mo 'ko tawagin ng nanay, hindi kita anak! (Do not call me mother. You are not my son!)
.....Which brings to an end the idea that all Pinoys are related.