Yes you can place the Copper Chef Lid in the oven with the Copper Chef Cookware and it will be perfectly safe.
I have placed the Copper Chef Cookware in the oven with the lid on it when needed and it's never broken and is designed to withstand the heat in the oven according to the Copper Chef Cookware cookbook.
So if you want to use the Copper Chef Cookware with the lid on it in the oven you can do so but be aware that the lid and handles will become hot in the oven.
So make sure you wear oven mitts before handling the lid of the Copper Chef Cookware.
But it will be perfectly safe in the oven to keep the Copper Chef Lid on it.