It is possible that the formations of FGWs' hybrid 3-car 158s has changed since 158960/961 were formed up earlier this year. However, as far as I know, and as I noted them at the time, their formations are as follows:
158960: Formed of 158769 plus one carriage from 158749.
158961: Formed of 158767 plus one carriage from 158749.
158749 has been split between the two sets to bring them up to three carriages.
As for the first unit in your list, do you perhaps mean 158958?