you cannot group the normals in blender, however there is a very easy workaround to this problem that I have used myself. go into edit mode, tun on show normals.

then, select the faces of the normals you want to group, press alt+n or find normals in the mesh dropdown and then press point to target. nothing will happen click anywhere and you should get something like this in the bottom left corner of blender

set the z to the z location of the normal in the world. then set the target as far from the model as possible without changing the final result(the farther the better this is extremely important) this does need a bit of tweaking afterwards but for the most part it has worked for me.Hope this helps.

you cannot group the normals in blender, however there is a very easy workaround to this problem that I have used myself. go into edit mode, tun on show normals.

then, select the faces of the normals you want to group, press alt+n or find normals in the mesh dropdown and then press point to target. nothing will happen click anywhere and you should get something like this in the bottom left corner of blender

set the z to the z location of the normal in the world. then set the target as far from the model as possible without changing the final result(the farther the better this is extremely important) this does need a bit of tweaking afterwards you can do this by switching to vertex select mode then selecting one of the normals you tried to group that is working as intended then press alt+n and press copy vectors then select the vertices that are not working properly one by one and press alt+n and press paste vectors.Hope this helps.