Physical Animation Blend Weights Bug when trying to simulate only a bone while keeping Simulate Physics active

I’m trying to create a system to manage physics animations on skeletal meshes and I can’t find a way to simulate the physics of the entire mesh (including a specific bone) and then no longer simulate the physics of the entire mesh but continuing to simulate that specific bone, for example the arm. given that if I set all bodies below simulate physics on the pelvis as active and subsequently set all bodies below simulate physics on the pelvis as inactive and immediately after set simulate physics all bodies below as active on the bone (for example the arm), the position of the arm is reset I thought of using blend weights. basically I set simulate physics on the active pelvis, then I set the global blend weight to 1, after a while I set it to 0 and set the arm blend weight to 1 to simulate just this. trying to obtain this result I ran into the following problem: if I set the pelvis to simulate physics and then set its blend weight to 0 and set the blend weight of the arm to 1, I get this strange result as you can see from the video . How can I get what I want?