How to scale a bone without affecting it's children?

[Feas]

I found the answer! My version is ue 5.3.

1. Create a ,Blend mask, in the mesh or skeleton editor. Assign index 1 to the desired bone.
   

   

2. In AnimBP make a blend with a mask and transform the desired bone through Transform bone and check the boxes as in the photo against Mesh Space Scale Blend.
   

   

3. After that, everything should work!!!