Looking for Mom.

Looking for Mom.
Hello.
I am Yoo Kyung-sook, 55 years old (Korean age).
My mom's name is Kim Hye-soon, and she's about 73~75 years old.
Since we parted ways less than a year before she was born, we don't know her face.
My dad is Yoo Young-kyu, and after he introduced me to a senior at school, I married my mother's older sister. That daughter is 55 years old (Korean age), the same age as me, and her name is Go Soo-jin. I understand that she immigrated to where my mother, Kim Hye-soon, lives in 1988, the year the Seoul Olympics were held.

He married in Korea in 1981 and immigrated to Australia, where Ko Soo-jin (13 years old) played the piano at their wedding.
Afterwards, I heard that the mother gave birth to two sons.

I tried to look it up in my twenties, but it was difficult due to the distance between Korea and Australia and the lack of information. Now that the world is communicating,
I'll try again.
Dad passed away at 51
I have long missed my mother since I was young.
I became a mother of two sons and one daughter, and now all three of my siblings are adults.

I'm now at the age to see my grandchild, and although I've never hated my mom, I've reached an age where I can truly understand her.
My mom is now at the age of becoming a grandmother, so I think I must find her before she passes away.
After that, there's truly nothing you can do about it.

Please help me find my mother.

From Seoul, sending Yoo Kyung-sook