Partially joining multiple M365 domains

[Ditto]

A number of charities are collaborating on a project and many of them have there own M365 accounts and MS Office suite. Some will have in house IT admin will have a third party support. Increasingly, there is a demand for closer working. As an example, the partners would like to be able to see each others Outlook calendars for meeting bookings, to collaborate with MS Team across the charities in the same way as do within their own charity. I guess it would perhaps be similar to what might be need if a number of schools came together in a MAT. So the question is, what steps would each partner need to take to enable this.

 

Longer term, it may be possible to bring all the accounts together under a parent domain, but I think each charity would still need their own domain/account control too as although the charities are collaborating on a project, some of the charities will be working in parallel on other projects.

[Roberto]

So you can share data in Exchange Online / Organization / Sharing between M365 tenants to share free/busy info for meetings, for example. That's not a problem.

You can ultimately have multiple domains brought into the same M365 tenant too if you prefer. There's about 200 domains in the tenant I help manage right now.

Edited February 12, 2021 by Roberto

[chaplic]

It doesn't sound like these organisations are merging, so all being in the one tenant is not appropriate

 

As roberto says, you can setup free/busy sharing to make booking meetings easier

 

I'd suggest you pick one tenant to be the collaboration point, and invite the people from the other tenants as guests so they use their existing credentials. Use Teams as the collaboration hub.

 

Guest accounts can be shown in the GAL if you choose for the tenant everyone's collaborating in, for the others you could manually create contacts so that people can be found, or find a way to automate it.

[Ditto]

Correct, no mergers anticipated, but the dozen or so charities are going to be working on a common project for up to 10 years, so over time collaboration should increase. The partners have formed a legal partnership, so in the long run there could be more centralised approach, but I don't think anyone is ready for that yet. Easier Teams collaboration is likely to help beyond calendar sharing, but I suspect changes will be incremental.

[chaplic]

Id normally never suggest another tenant, but perhaps in this instance it's appropriate. A new tenant, owned by the legal partnership, then everyone is guested in/out, used purely for teams (youd still do the free/busy stuff per each charity). Would mean no ownership issues with data if one partner leaves?

[Roberto]

Id normally never suggest another tenant, but perhaps in this instance it's appropriate. A new tenant, owned by the legal partnership, then everyone is guested in/out, used purely for teams (youd still do the free/busy stuff per each charity). Would mean no ownership issues with data if one partner leaves?

 

This isn’t a bad idea, especially when you consider potential safeguarding and data protection issues being just a default setting or mis-configuration away if allowing lots of external guests to have access to one org’s tenant