To be able to script an alternative targeting system (ie WW2/some helper system) or a more advanced system, please add the following two commands:

SQF commands:

_target = getTargetLock _unit;//objNull if none locked
_success = _unit setTargetLock _target;//false if lock cant be set for any reason

Ref: https://community.bistudio.com/wiki/Arma_3:_Targeting