Firstly, I am not a user of Cases, so I hope someone can build on these steps and point you to the specific component you need to make the change. Therefore, I upload these as more a guide to how I would go through finding this structure myself.
Next, I assume you will be doing this from your development environment. Therefore, you would open a Solution, as suggested by Charles. If you haven't used solutions before, read the intro:
[View:https://docs.microsoft.com/en-us/dynamics365/customer-engagement/developer/introduction-solutions:750:50] (pay particular attention to managed/unmanaged).
Then follow the creation steps for a new Solution at:
[View:https://docs.microsoft.com/en-us/dynamics365/customer-engagement/customize/create-solution:750:50]
Steps after adding a solution:
1. Now, you most likely want to start with adding a Process to your solution. In the long left-hand menu of the solution you have created, find Process (this is where your Workflows live, as also suggested):
2. Now, click on Add Existing to scroll through all your processes and workflows:
3. Admittedly, I don't use Cases, so not sure which work flow you need. Let's say that this is driven by the Case to Work Order Business Process. However, look through the list and find the most likely Select that process by clicking on it to tick it, then click OK:
4. It will now appear on your Process list in your solution. Double click it to open it. Now, check it out and see if it looks familiar. If it is the right workflow, you can start updating it by adding and removing components, or it sounds like you need to check out the corresponding Business Rules:
5. You may also want to check Business Rules on the entity.
a. Add an Existing Entity
b. Select Case
c. Note, when it asks what parts of the entity to bring across, I would recommend selecting "Add All Assets" in the top right hand if this is the first time you have done this. If you know exactly what you are doing, you can be far more specific as to what you want to bring across.
d. And keep the existing radial button. Again, not normally recommended, but I find you have problem promoting if the Missing Required Component is the actual Entity you are adding. On the downside, this often means you have to bring across a range of other entities due to relationships. You are best to ascertain the actual requirements during Import of the Solution to your test environment, rather than on Export.
6. Once the Entity is on your left-hand menu, open that entity and check through each of the subcomponents of the entity to check if any of these control the Case structure you are looking to address:
7. Lastly, if you can't find it in any of the above, you may find that you are working with a Web Resource. Again, this is in the left-hand menu and takes a long time to load, so be prepared. If it is in here, it will most likely be a script and you'll have to put Java knowledge to use. This is probably how you'll end up adding a Comment Button. Try some instructions like this:
https://community.dynamics.com/crm/f/117/t/265943
Hope this provides some help. Still, if someone can answer you directly and specifically, you'll be better off.
