How do I get the selected rows in json format from a nested grid and then export those rows in excel format?

I am trying to get the selected rows in the following grid in json format and export

http://jsfiddle.net/8198ykLv/1/

Something like that:

selectedItems=[
{
   companyName:'Facebook'
   contactName:'Mark'
   Manager:[
             {
               manager:'Jake',
               phone:'34545645656'
             },
             {
               manager:'Phil',
               phone:'66667878'
             }
           ]
},
{
   companyName:'Twitter'
   contactName:'Lol'
   Manager:[
             {
               manager:'Mike',
               phone:'68678'
             }
           ]
}]

And then export the selected rows in excel format considering the json levels.

Consider that if I select a child, the parent's checkbox must be partially marked and if I select all the children, the father's checkbox should be checked.

Please your support, I know that you are the best community, I await your answers, thank you.

http://jsfiddle.net/8198ykLv/1/