How to create 3 Level of Parent Child grandchild Table Grid

I wish to create 3 Level deep Master / Detail using One of the Gird or multi row Table (Parent -> Child-> Grandchild)

For example Customer Table > Order Table L1 > Items  Table L2 > Item Detail Table L3

From Customer Form one should be able to add Orders in a GrildList, for each Order one should be able to add multiple Item in the 2nd Gird and then on third Level user should be able to add item details to each of the Items in a List Gird.

Once the parent is saved all three Levels should be saved.

I tried using "Grid Form" but as this is Pop up by based the child screen by the 2nd screen got unusable and had to change the window size. I am looking for a way to Open the child in another window.

I was not able to find an example where on the Child Form there is also a another Gid Layout.

Ideally would like to have all of the all 3 grids on the same screen. 

It would be nice to have a video of this Tutorial