英语翻译Soon Jim,16 and Emily,13,the youngest of our four childr

英语翻译
Soon Jim,16 and Emily,13,the youngest of our four children,will help me make some long-overdue improvement on the outdoor toile that supplements our indoor plumbing when we are working outside.
过些时候,四个孩子中的两个小的,16岁的吉米和13岁的艾米丽会帮着我一起把拖了很久没修的室外厕所修葺一下,这是专门为室外干活修建的.
我的疑问：
这里的that supplements our indoor plumbing 在句中如何翻译?