 Okay, so your character isn't exactly the same as the Unreal Mannequin, and you're not sure how to augment the skeleton. Not a problem. So here you can see that we have the original Unreal 5 skeleton straight from the engine, and it really only has bones that a normal human being would have. So if you're making like cat girls that have ears and tails, then you're obviously gonna need to add some more bones. So the question is, how do you do that without f***ing up the skeleton? Well, the rule is pretty simple. You can add whatever bones you want, no problem. You just can't delete the old bones. So for example, my character has more feminine proportions than the original Unreal 5 Mannequin. So if I wanted to add new bones to control the boobs, then I can really just go ahead and add new bones. And if I want to do the same thing for the butt, it's basically the exact same process. We can add those new bones too. Adding new bones is not a problem. But if you do something like delete the left hand, even if your character has no hand, when you export to Unreal, then Unreal is probably gonna scream at you and tell you that it's missing some bones. Now the second thing that you really have to be careful about is not f***ing up the rotation of the joints. Unreal and Maya share a rig joint system. Blender operates on a bone system. This is why Unreal works very well with Maya, but doesn't really work well with Blender. Every single normal rig joint has a direction and a rotation. And if you want to be able to use Unreal 5's retargeting and replacement animation system, then your bones need to share the same rotation as the originals. This is why most people's rigs fall apart and need to go through major retargeting when they get to Unreal. A lot of beginners make the mistake of dragging the joints like this to fit their character. But watch what happens to the rotation of the hand if we try and do that. I want you to pay attention to the direction the hand is facing normally. Now if we move it up here to fit our character, it might seem like nothing is wrong. But check out the rotation. See that? It still thinks it's facing this direction, even though it clearly should be facing towards the fingers. The easiest way to get around this is when you are adjusting the original rig to fit your new character, move and rotate the skeleton joints naturally. Do not drag them around to a new position one joint at a time. Rotate them naturally until they are organized the way your character needs them to be. If you do it this way, your rig is way more likely to make it to Unreal without any errors. Now I personally have made my own custom joint system specifically to help me with this purpose. If you would like to use my Unreal Skeleton placement system, you can download it for free from my art station. Basically the way it works is it uses nerves that are oriented exactly the same way as Unreal 5's skeleton, which I can then move, stretch or rotate and place exactly where I want for my new character. The reason this system helps is because I disable the nerves from being able to rotate, move or stretch in ways that would break the skeleton. So for example, the hips can basically go wherever you want and you can change things like the length of the legs, the lengths of the shins and the lengths of the forearm, but you can't actually rotate them in ways that would break them. The only direction you can rotate them is in ways they naturally go. If you are using my system then it's pretty straightforward. Disable all these selection types except for nerve. Start with the root bones first like the pelvis, then work your way outwards to the outer limbs like the hips, the shins, the toes, and while you're doing this you might notice that the twist joints in the middle of the hips, shins, biceps and forearms all adjust themselves automatically. So you don't need to manually move them into places. Just go through each joint and rotate or extend it naturally until everything fits your character. And everything is mirrored in real time so you only have to do things once on the left side. And remember all of the real IK and FK rig stuff is controlled and unreal. The only thing that matters before you get to unreal is that the joints and skin are weight-painted properly. So once you've placed all the joints where you want you can then start adding your new joints for your ears, your tails, your chest, but whatever. Weight-painted the way you normally would and export to your engine guilt-free no errors necessary. Now if you do get errors like the bind skin error then my free skeleton system also comes with the mail script that you would need in order to fix those errors. So basically you just follow my previous tutorial and then copy and paste the last piece of code in this text file to create a new bind pose and get rid of the error. So that is a completely free option that is available to you if you need it. But yeah that is how you edit the skeleton without breaking it. Hope that helps and as always I hope you have a fantastic day and I'll see you around.