Problem assigning different users to same phone #

I have been setting up a group account for 35 inReach Mini 2s. The users they will be assigned to I have no way of knowing their existing phone numbers - but the radios need to be active with the ability to send messages when they receive them. 

Garmin Explorer Group Plans allows me to create multiple users with the same phone # - as long as they have different email addresses. My question is - will this cause a problem? The radios claimed they sent messages when not assigned to users, but the messages never went thru. After creating a user it worked. 

It appears to work to have multiple users sharing the same phone # - but with no feedback from Garmin unit that it couldn't send messages without being assigned to a user (while appearing to send) - can anyone tell me if all sharing the same phone # is going to be an issue?