Populating Contact Column - Multiple rows with single cell entry

Hello Folks, 

I have a new employee onboarding Smartsheet template I created with 100's of rows / tasks for various departments to complete and I need to set reminders up for different dates (10 days prior to starting work, the day prior to starting work, day one of work, first week of work, onboarding follow-up and 90 days after) to go to different departments or the hiring manager. 

My directive is the Hiring Manager (can be one of six individuals) shall do minimal data entry to get reminders to send on the appropriate date.  I have it down to entering the new employee name, start date and end date and have built formulas into the Start Date column to send the reminders on the correct date to generic department email address which are static and do not change.  These work fine and are good to go... 

My issue is the hiring manger can be 1 of 6 possible managers and their tasks need to be sent to their personal email address.  There are 60+ tasks scattered through-out the Smartsheet for the hiring manger.  I need to be able to populate the rows with the appropriate hiring mangers email address (contact column) without their having to go to each row.  As it can be 1 of 6 email addresses and contact columns do not allow formulas, I am having a heck of a time trying to come up with a solution so the hiring manger can enter their name into a single cell and have their email address populate the 60+ rows / tasks so the reminders can be sent when the date hits. 

Any suggestions on how to handle something like this?