How to download Multiple animate from mixamo and then edit one of these in blender and then input it to ue5 agein

[n0o_o0h]

I download some animate form mixamo(FBX),first i input the stand to ue5 with nothing change.It get a “MixMaoStand_Skeleton”.
Then I download other animate withoutskin,and input by select “MixMaoStand_Skeleton”,It works great.
But and then,I want change one animate ,so used the “mixamo FBX input” addon input to blender.Just add som “Keyframes”,output fbx again.
Final input to UE,Get a Horrible Animation
How to make this Correct. THX