Dependency map — Alder Group and Bexley Holdings
How to read this
Every line names something that cannot start until something else is true, and why. The three kinds are not interchangeable. A platform constraint is not negotiable. A sequencing constraint can be reordered, and the cost is rework. An operational constraint belongs to one of the organizations, and can be renegotiated with the person who owns it.
- Platform
Enforced by Microsoft 365. There is no order of work that avoids it. - Sequencing
Can be reordered. The cost of doing so is rework, and it is named where it is known. - Operational
A constraint of the organizations rather than of the platform. Recorded here so it is not mistaken for one.
Dependencies
Item
Mailbox migration for a bexley.example user
PlatformCannot start until
That user exists and is licensed in the alder.example tenant
Why
A mailbox lands in an account that already exists and already holds the license. There is no create-on-arrival.
Item
Claiming bexley.example in the alder.example tenant
PlatformCannot start until
The domain has been removed from the bexley.example tenant
Why
A domain verifies in one tenant at a time. Everything addressed at it moves with the claim rather than with the mailboxes.
Item
Shared mailboxes, distribution groups and aliases at bexley.example
PlatformCannot start until
Those objects exist in the target before the domain moves
Why
Mail sent to an address with nothing behind it does not queue. It bounces, and the sender is told so.
Item
Second-factor registration in the target tenant
PlatformCannot start until
The user has a target identity and a route to register against it
Why
Registered methods are tenant-scoped and do not travel. Every user re-registers, and the interval where they cannot is a lockout.
Item
Device enrollment for a bexley.example device
PlatformCannot start until
That device's user exists in the target tenant
Why
A device enrolls against a tenant identity. Re-enrollment is the operation; there is no transfer between tenants.
Item
Power Platform environments and their data
PlatformCannot start until
Does not move — a decision, recorded in the remediation register
Why
Environments are bound to the tenant they were created in. Rebuild, retire, or leave in place under a temporary arrangement; there is no migration path to sequence.
Item
Teams channel cutover for a team
SequencingCannot start until
The SharePoint site behind that team has moved
Why
Channel files live in the site. Moving the team first strands them, and the rework is per team rather than per file.
Item
OneDrive content for a user
SequencingCannot start until
That user has signed in once against the target tenant
Why
The library is provisioned on first sign-in. Until it exists there is nowhere for the content to be written.
Item
Re-sharing content that carried external links
SequencingCannot start until
The content has landed in the target
Why
Sharing links are rewritten by the move. The links are not content and are not carried across with it.
Item
Repointing applications that authenticate against bexley.example
SequencingCannot start until
Target identities exist and user provisioning to the application is re-established
Why
An application repointed before its users exist authenticates nobody, and the failure surfaces as a login outage rather than as a migration step.
Item
Retiring directory synchronization at bexley.example
SequencingCannot start until
Every object it still owns has been migrated or converted
Why
An object that loses its source of authority becomes unmanageable in place, and recovering it is slower than sequencing around it.
Item
The mail routing cutover window
OperationalCannot start until
bexley.example's month-end close has completed
Why
Named as immovable by their finance lead. Not a platform limit, and it is recorded here so nobody later argues with it as though it were one.
Item
Decommissioning the bexley.example tenant
OperationalCannot start until
A decision with a date, taken after validation has been agreed
Why
Nothing is decommissioned as a side effect of the last wave completing.
Open questions
Each of these changes the plan. They are listed rather than assumed, and they are what the review meeting is for.
- Is the on-premises directory at bexley.example retained after cutover?It decides whether those accounts are converted in place or created fresh in the target, and the two produce different remediation work. Until it is answered, the synchronization entry above has no scope.
- Which applications authenticating against bexley.example are still in use?Two have no named owner. Repointing an application nobody uses is wasted work; missing one that is in use is an outage on cutover morning.
- Does the target conditional access baseline apply to arriving users on day one, or after a registration window?It moves the lockout risk from during the cutover to after it. Both are manageable; they are not managed the same way.
- Which Power Platform environments have an owner willing to rebuild them?The ones that do not are a retirement decision, and it is the client’s to make rather than ours to assume.