Make GameObject child of a child

I have a problem when placing a GameObject to be a child of a GameObject .

The current code make sub of pastsUpgrade[1], how can i make be sub of gridGameObject?

subButton.transform.SetParent (partShopItems[counter].transform);

Example in folders representing gameobjects (please consider partShopItems[counter] as partUpgrades[1] in image)


Solved using this : partShopItems[counter].transform.Find(“SubUpgradesGrid”)