Make sure they use their company email address.
You like Roleshare and want to use it for enabling job-sharing in your organization. Great!
To invite employees in your organization to Roleshare, simply ask them to signup to Roleshare using their company provided email address (containing your company-specific domain).
Once they sign up to Roleshare using their company provided email address, they will automatically be shown as employees in your company account.
They will also be able to see other employees open to job-sharing and connect with them.