This is a fanmade Sing-a-ma-jig quartet. The big one is chartreuse, has the same ears as the Light Blue Sing-a-ma-jig, black circle eyes, a blue nose, a pink mouth, the same hand pose as the lime green one and the same feet as the big one from the Dark Blue duet. The babies have the same ears, hands and feet as the little one from the Orange duet. The orange teddy bear has dark blue circle eyes, a light purple nose and a yellow mouth, just like the big one from the Orange duet. The red teddy bear has blue circle eyes, a purple nose and a blue mouth, just like the big one from the Red duet. The blue baby has black circle eyes, a yellow nose and a pink mouth. They sing "John Jacob Jinglehiemer Schmidt".
Here are what their voices sound like.
Big one: Lime Green
Orange Teddy Bear: Little One From the Royal Blue duet (While harmonizing in the same voice as the Birthday Soprano)
Red Teddy Bear: Mermaid
Blue Teddy Bear: Little one from the Fuschia duet