Instantiate object of class existing as a list in another class

So I have two classes Class A and Class B.

export class A {

aName: string
aBs: B[];

}

export class B {

bID: number
bName: string

}

Class A contains a list of objects of B. bID is unique. No two B objects can have the same bID. Every object of class B (with a unique bID) can belong to only 1 object of class A. What is the best way to instantiate B with a knowledge of which object of A it belongs to? Should I create another class AB which combines the two? But how exactly?