A way for a user to create other users?


Im working on an app for my final year project in college, but im currently having issues that im not sure how to work around, namely, i will have users which can create other users, there will also be references to these users in a firebase database, im having trouble gettin a new users id on signup as this will be the key for the new users reference in the database

signUpClient(email: string, password: string, name: string): any {
    var clientId: any;
    let details: UserDetails = {'email': email, 'password': password};
    //Create client
    this.newClient = this.auth.signup(details).then(() => {
      console.log("random test");
      clientId =  this.newClient.id;


    return this.newClient;

when this.newClient.id is undefined?