How to add a bone weight based on the weight of other bone

Walker

For example
Let's say there is an attachment bound to Bone 1 and Bone 2
But I create a new Bone3 as a descendant of Bone2 and bind it
I want to add weights in the Add Mode for Bone 3
If I simply adding it reduces the weights of Bone 1 and Bone 2 and assigns new weights
I want to fix this and repaint it with a new brush based on the bone2 weight used at each vertex of the attachment

Misaki

Walker I'm not sure if I understand your question correctly, but if you want to transfer all the weights currently assigned to Bone 2 directly to Bone 3, you can select the names of the two bones in the Weights view and click the Swap button.

If you select vertices before doing this, the swap will only be applied to the selected vertices. If no vertices are selected, it will be applied to all vertices in the mesh.

If you only want to assign part of the weight currently assigned to Bone 2 to Bone 3, you can lock Bone 1.

This allows you to paint weights for Bone 3 while keeping Bone 1's weights unchanged, so only Bone 2's weights are reduced as weight is assigned to Bone 3.

Walker

Misaki
Swap wasn’t what I meant, but
What I'm looking for is a locked bone
Thank you.