Coil Lock out Question

Situation: We cleared turn 4 while turn 5 was disabled and we have not been in it yet. One of our tanks won't be on tonight.

Can we take a tank from another one of our FC's group? Will it lock him out of turn 1-4 for his group if he just comes into turn 5 with us? Or is the lock out triggered on killing the turn 5 boss.

The moment another person steps foot into an instance in progress they will be saved up to the point the party leader is at. It does not matter whether a boss was killed or if someone got invited for some wipes, they will be saved.

Ok thanks, so no turn 5 tonight ><