This is perfect, @kelfire! Thanks for the tip.
I know this is kind of old, but reading through the thread I can see a few people struggling with these steps in Blender. Since others will probably land here through search, here’s my contribution:
– For those of you having trouble with in-place animations in Blender –
Step 10) Import the original UE4 Mannequin with root…
\ …then you need to un-parent SK_Mannequin from root. Click on root, then in the viewport, press Alt+P > Clear and keep transformation. Blender interprets “SK_Mannequin” as an empty, which UE4 will see as an extra bone.
Step 11) Import one animation downloaded from Mixamo to original UE4 Mannequin…
\ …then copy the animation to the UE4 Mannequin imported in step 10. The easiest way to do this is to first select the UE4 Mannequin’s armature, shift select the armature containing the Mixamo animation, and create a data link by pressing Ctrl+L > Animation Data. Now you can delete the no-root Mixamo assets and import the rest to UE4.