How to add additional joint bones to unity rig setup ?

Hello, Created rig and animations for character. In unity ican see problems with additional bone joints. Only joints that rotates or move is ones assigned in rig of unity character setup. I have 4 joints in character belly area, and unity lets select only one.

  • Is it possible to add these additional bones to hierarchy of unity rig setup ?

What I did was removed extra joints in skeleton, and re-skinned everything to match unity 3D defaults.