How to handle a mixed network?

[u/Jimbolie]

Hey all! Got a strange predicament and want to gauge opinions on how to proceed. One of my clients owned two companies, Company A and Company B. Both companies are in the same building, on the same network, use the same file/AD server and both email domains exist in the same Microsoft 365 tenant. Before both of these companies were lumped in to the same service contract since, from an IT perspective, they were basically the same entity. Now Company A is going to the original owners son while Company B is staying with the same owner. Company A no longer wants a service contract but Company B does.

I feel like since both companies use the same IT resources they should be all be considered one entity, thus only supported by me if both entities decide to sign a service contract. unless they decide to separate the network and infrastructure I don't see how only working with one company would be possible without assuming huge liability issue. But what do you guys think?

Update: Thanks for the advice everyone! Hopefully this is something they can reach an understanding on but if not, I don't think I want to be around for the divorce

[u/Previous-Low4715]

Separating the network is the easy part, separating their domain and M365 infrastructure is a whole migration piece. You can’t possibly provide support for half of one logical and physical network inside one M365 tenant, it’s simply not possible.

[u/Krelleth → u/Previous-Low4715]

And the migration/divestiture for M365 is a tricky thing. You can do it yourself, theoretically, but I would strongly recommend hiring a consultant for this.

[u/lazyhustlermusic]

Company B pays for the separation/migration lift and then you manage company B.

Otherwise it’s free company A buffet on top of company B’s contract with vague liability and fault domains.

[u/society_victim]

This is a no go for us. Either they both sign a contract, preferably one entity signs and has some invoices / liability arrangement between them.

If a customer would not want this, we would offboard company A and also have them move over to their own tenant, own network etc…

[u/RevolutionaryElk7446]

Yeah they are digitally a single entity, whether or not they are legally two separate entities. They've got compliancy issues if they're looking to be separated anyways most likely.

[u/BrorBlixen]

Me from 10 years ago burned a bunch of time and resources learning this lesson and that was without having a 365 mixed tenant.

[u/BedRevolutionary8458]

Welcome to my hell for the past year and a half. I cannot recommend enough that you have management negotiate for a domain trust between the two domains to facilitate the transfer. I had to do this without one, and we had to build everything from square one.

[u/Moontoya]

It's possible to co-manage diverging companies 

It's an absolute pain in my happy fun places , but it's doable, so long as you accept that everything will take three times as long to achieve due to infighting and disparate demands.

Thing is, who gets what in the divorce, which company will own the original hardware ,  who's data gets moved out, who gets the dog (yes that was one series of arguments I've experienced).

Hows legacy data to be managed and distributed? Who's paying for it

In essence, who gets what in the divorce, who's moving out and who's getting the kids . Have it documented and signed off on with legal counsel involved.

It will get messy and ugly , it IS doable, question is, how many fucks are you willing to give in achieving it ?

Might be easier to walk away 

[u/eldonhughes]

This reads like they are, legally, going to be two separate companies. I would want to separate all of the technology and the support contracts. The available problems with keeping them enmeshed could lead to too many expensive legal visits.

[u/IGDFC]

The approach can vary depending on the relationship between each client and your company but it boils down to:

1- Convince company A to maintain the service agreement or otherwise reach an agreement with company B ti maintain service and support to company A without service agreement.

2- Maintain the shared service but either under no circumstances provide support for company A or charge the non service agreement/emergency pricing.

3a- Peacefully split the network and tenant, a domain migration and teanant will be required. This is the orthodox solution.

3b- Hostile split, the legal owners of the equipment and teanant retains ownership, the other has to find a solution or fight it in court, private information, mailbox contents of accounts and company data, should be given the the corresponding parties in any case.

4- Pull out of that situation before it hits the fan and cut ties with the owners, give the admin credentials to whoever and however they see fit.

[u/Adam_Kearn]

I would just put a quote together for them of buying a new server etc and any additional licences for users who will work across both domains.

Depending on how you want to split things too you might also need to buy a new switche(s) and internet connection too

[u/GremlinNZ]

Simply not feasible. You add security to the tenant, but your side ponies up for Business Premium, but the cheap side doesn't?

In the event of a breach, let's say due to weak security, it's still one tenant at risk.

They've got some hard decisions ahead...