Since 1.12 you can see the recipes. Normal Recipes of CC are listed, but not upgrade recipes. A Example for Upgrade Recipe is to craft a mining turtle with a turtle and a Pickaxe.

I think (not currently on computer so haven't tested) that the main issue is advancements are not generated to unlock the recipes. Manually unlocking them with a command should work as expected. I'm pretty sure none of the dynamically generated recipes (turtle/disk/pocket dying, pocket upgrades) will have advancements, as creating them dynamically is impossible.

So this recipe is a pretty standard template - you'd just change the recipe name to be upgrade specific, and probably change the conditions to include the various items. There's documentation of the format on the wiki - I'm sure you can figure out the rest.

In order to avoid creating 24 different advancements (normal/advanced items, turtle/pocket computers) I'd suggest just creating an advancement for each upgrade, unlocking the upgrade for both normal and advanced versions.

For dying, you can probably get away with unlocking all 16 recipes in one go. Otherwise we'll end up with over 100 advancements, which will be very ugly.

@SquidDev I have added the Json and they are triggered, but there is a Problem:

How can I add the recipes as single Items and not as a alternative turtle recipe?

@Wilma456 You can replace the first argument of ImposterRecipe with an empty string in these lines.

However, I'd rather they were grouped together - many of the vanilla recipes do the same sort of thing and it means you don't end up filling the recipe book with near-identical recipes.

@SquidDev I think, I will left them together.

But just one Question: What does the data tag in

"trigger": "minecraft:inventory_changed",
            "conditions": {
                "items": [ { "item": "computercraft:computer", "data": 16384 } ]
            }

do? I want to replace it with the turtle and the advanced turtle for advanced turtle upgrades, but have I change the data tag?

The data tag is the item damage. You'll want to leave it as 0 in both cases.

If you show me, how the json Files for the Upgrades should look, I can use #468 to write a script, that create the json files.