Assigning People using IF Formula or the new Assign People Workflow?

I am setting up a request register where the client logs a request via a form. I want to then notify specific key people depending on what account the request is for to review the request and work on next steps.

The people sit in 3 key groups. Account Manager, Commercial Manager & Project Manager.

At the moment I have set up an IF statement in the register sheet in 3x Contact Columns to input the specific persons email based on the account name. Idea being that I then have a workflow that sends an alert to all 3 when the request is added to the register.

Q1. On some accounts there are 2xProject Managers so I have made the PM contact column open for multiple contacts. Is it possible to include the 2xemails into that column i.e. what is the syntax used to enter 2 email addresses into the one column?

e.g. =IF(Account@row = "ABC", "pm1@company.com", IF(Account@row = "DEF", "pm2@company.com", IF(Account@row = "GHI", "pm4@company.com ; pm5@company.com", "Error")))

Q2. Can this be done using the new Assign People workflow? I have not really used it, but what would be great is to be able to assign multiple people to the separate columns based on the addition of the row and the account being specified?

I tried looking at it but it only seems to allow you to set it for one person or multiple people into one column? So to use workflows I would need to set up 3xworkflows per account which makes me think the IF formula is better suited?

Hope that makes sense?

Thanks.