issue with creating material instance

Hello guys ,
i have issue with creating material instance, i want to make one material and make several instance from it and change textures depending on object material , so when i make material with texture 2d parameter and creating instance from this material the issue is some textures not working and this happen randomly like from normal once from ao or specualr/roughness once and another issue when i put like a new normal textures it’s give me new normal but above basic material normal so i have 2 normals above each other how i can fix this problems please .