Synchronize two animator states to have the same normalized time - Mecanim

I have a scenario where two avatars can carry each other on their shoulders. The upper avatar can change its orientation to look forward or look backwards.

When he changes its facing direction I need to synchronize the normalized time of the upper animator to be the same as the lower animator.

How can I achieve this? Basically the question is:

How can I set the normalized time of one animator to the same as another animator. And this means that after the correction both run with the same normalized time.