Start porcess from another process

HI guys,
my project has 3 process
the first checks the file and it sends email
the second computes data and it makes excel report
the third check email and re-start if necessary the second process.

the second process the first time is schedulated by orchestrator but the more times this process will be start by email answer, checked in othe process.

could me launch by “start job” from 3th process, or to use a boolean asset on orchestrator, or other way ?