You just need to move the joints further without the skinning being affected?
Because as far as I know, there’s no way to do that in engine, unless you’ll wait for 5.3 to be released, which allows the updated of the skeleton.
Or you would like to nove the joints together with the skinning?
If so, you can simply add two TransformBone node in the AnimBP before the “Output Pose” node, set them to “Add to existing”, then choose the proper axis to move and you’re good to go.