Not sure you can convince them. You have to remember that they know what it's like to be a parent and everything that entails incl cost. It also costs to adopt usually. You can make a list of why they should consider it and ask them why not. Adopting is very emotional though and they cannot change their minds. It's possible they now that you are older, feel like they have a good balance in life with each other, you and work.
well after the age of 18 it is unlikely for them to be adopted even as a younger sister/brother. You could call her/him your younger sister/brother but it would not be official
teina-younger sister of a female
Imouto is for your REAL younger sister and imoutosan for another person's younger sister.
In Lakota, a woman calls her younger sister mithan; a man calls his younger sister thankshi
because she rocks and she is the younger sister.
yh she did fight her sister when she was younger
he has a younger sister called Megan
Younger sister has no such specific word in hindi. Its just CHOTI BEHEN where CHOTI is younger and BEHEN is sister.
She had one younger sister.
Filipino translation of younger sister: Nakababatang kapatid na babae Note: Younger sister in Filipino is called depending on the order of birth of the sister. This is how younger sister is called. ate- eldest sister ditse- second sister sanse- third sister bunso- youngest sibling
Your younger sister will grow if you feed her.
Her Younger Sister was created on 1914-12-15.