Usually when i share a site with external users, i do the following steps:-
Enable external sharing on the related site collection.
I add/share the external users email addresses to a site collection's group (ie members group).
Then the external users will receive an email, and once the external user login to sharepoint, his/her email address will be added a Guest account inside office 365, and will have this format
but now i am facing this scenario:-
we have sharepoint enterprise on-premises 2013. and we have 10 external users' accounts added to our on-premises active directory (those represents a partner company which have separate domain), and those external users were accessing the the on-premises sharepoint sites using VPN.
now i am using a third party tool named sharegate, to migrate the on-premises site collections to sharepoint online.
But i want to map the on-premises external users to new external users (Guests) accounts. and to be able to do the mapping i have to add the external users in-advance to office 365 . so i am not sure if i can replicate the above 3 steps manually ?.. in other, words; can i without sending the external users invitation emails , to have their accounts added inside office 365 as external users (Guest)?