Siblets. 

A group of young people, which includes your own children, and/or children of former partner or partners, regardless of parenthood.

We are having a party and inviting all the siblets.

Siblets. by johnlephoto November 23, 2021

sibless

Only child, i.e. without bothers or sisters.
No siblings.

My "sibless" son is sometimes lonely without brothers or sisters.

sibless by George Rouail October 15, 2010

Siblents 

/‘sibl(ə)nt/ n. Pl. 1. A joint name for uncles and aunts. Portmanteau of “siblings” and “parents.” 2. One’s parents, uncles, and aunts considered collectively.

Original Definition: A joint name of uncles and aunts taking from sibling and parents.

I am going to see my siblents today.

Siblents by ButterCCM January 13, 2020

Siblet

Gender neutral term for nieces and nephews.

I took my siblets to the park yesterday.

Siblet by kashlyn May 7, 2015

Siblits 

A legend, an absolute fucking legend.

1: Siblits was a legend, I wish he was still here.
2: 😢
1:😢

Siblits by ssurt_ October 14, 2021

Sibles 

Some white kid that brags about being a minority and likes making cracked joker impressions.

What a sibles... his father is not a criminal.

Sibles by Jhaan June 13, 2022