there are multiple levels of tab and step, in state. It is very painful to modify a deeper level of state. How to split reducer?? Or how to flatten the reducer?

var tabs = [
    {
        id:1,
        children:[
            {
                id:11,
                steps:[
                    {
                        form:[
                            {
                                name:"foo",
                                type:"input"
                            }
                        ]
                    },{},{}...
                ]
            },
            {
                id:12,
                steps:[{},{}]
            }
        ]
    },
    {
        id:2,
        children:[]
    },
    ...
]

for example, if I want to change the Foo value in state above, I need to find tabs [0] .children [0] .values [0] .form[ xx] .foo = "boo" , which will be very painful. How can it be simplified?