如何单独更新'BehaviorSubject'单个值

在我的 BehaviorSubject 具有2属性的address元素。在这种情况下,如何单独更新单个属性?

以下是我的尝试:

myAddress:any = {
    "plot":32,
    "street":"D15 Road"
  }

  private address = new BehaviorSubject(this.myAddress);
  addressClass = this.address.asObservable();


  updateAddress(newAddress){
    this.address.next(newAddress);
  }

我正在尝试这样更新:

import { Component, Input, OnInit } from '@angular/core';
import { SharedObject } from './shared.object';

@Component({
  selector: 'hello',
  template: `
    <h1>Hello {{name}}!</h1>
    <h2>City Name in Hero : {{heroName}}</h2>
    <h3>{{plotNo}}</h3>
    <button (click)="updatePlot(44)">Update Ploat </button>
  `,
  styles: [`h1 { font-family: Lato; }`]
})
export class HelloComponent  {

  @Input() name: string;

  plotNo:number;
  address:any;


  constructor(private shared:SharedObject){

  }

  ngOnInit(){
     this.shared.addressClass.subscribe((address) => {
       this.plotNo = address.plot;
     })
  }


  updatePlot(newNo){
    this.shared.updateAddress(newNo); //don't know how to update plot no alone?
  }

}