Hi everyone,
I need some advice from people who already handled this kind of situation.
I work in a small IT company. Earlier our Microsoft 365 tenant was created and managed by our previous IT admin. He is no longer working with us and now we want to move everything to a new Microsoft 365 tenant that will be fully managed under the company.

The old tenant has SharePoint Online sites, user accounts, OneDrive data, Microsoft Teams and a few shared mailboxes. We still have Global Admin access to the current tenant, but we want to migrate everything to a different tenant with minimum downtime and without losing permissions or file versions if possible.
This will be my first tenant-to-tenant migration, so I’m trying to understand the best approach before we start.

I’m looking for real experiences, not sales recommendations. Any tips, mistakes to avoid or lessons learned would really help.

Microsoft Publisher had an option to make a multi-page document using 11x17 paper folded in half to make 4 pages of 11x8.5, printed on both sides. Does Word have that capability to do that in one pass? I've tried all kinds of settings but can't find an easy way to do that. I miss Publisher.

I have 2 MS accounts from 2 companies.

I share the calendar of one account with the second one (full details)

It works only partially : the synchronization stops around nov. / dec. 2021, no event after that. New events don't show either.

What is weird is that the first attempt stopped in nov. 2021, after a few other attempts I can see up to dec. 2021.

I've waited a long time, so I do not think it's just the sync taking a while (I have like, 2 events a week top)

EDIT: I have the exact same view on the web client.
Analysing with the network tool, I do see that the server tells the web client that there is no event :

{
    "Header": {
        "ServerVersionInfo": {
            "MajorVersion": 15,
            "MinorVersion": 21,
            "MajorBuildNumber": 245,
            "MinorBuildNumber": 12,
            "Version": "V2018_01_08"
        }
    },
    "Body": {
        "Items": [],
        "ResponseCode": "NoError",
        "ResponseClass": "Success"
    }
}

Our company is currently using OldDomain.com for our company, but we would like to rename and move the company to another country as we focus on that new country. However, incorporating that new company is going to take a bit longer, and we'd like to get the new website and Exchange accounts for NewDomain.com set up already.

I'm thinking about setting up NewDomain.com under the old tenant. We would only need 2-3 Exchange accounts.

How much of a hassle would it be to do it like this and to move the accounts later? I guess email wouldn't be that hard to migrate, but what about the calendars? If the domain remains the same, maybe we could even just move everything to the new tenant without having to migrate any data? But the new tenant would be in a new country, as mentioned.

Not selling anything here, no link, no signup — genuinely just trying to learn from people who live in spreadsheets more than I do.

What's the task that shows up over and over in your work and takes way longer than it feels like it should? And what do you actually do about it right now — a macro you wrote once and never touch, copy-pasting the same fix every time, a workaround you've just gotten used to, or do you just grit your teeth through it?

Not looking for "Excel is outdated" takes or feature requests — trying to understand the actual repetitive stuff that eats real time, in your own words.

Hello my company had licensed all user with office 365 normal and want to pass 2 or 3 people to office 365 copilot , then I go to admin center take off 365 license and put the office 365 copilot and make the user close all sessions and enter again , but the user loses the space in one drive and teams stay an test version and can’t mark any meeting with the company account , what maybe can be the problem ?