Duplicate companies with several domains or subsidiaries in Attio

Last checked November 7, 2026 · Deduptio is our product. Every claim about another tool comes from its public site or documentation and is linked in place — tell us if something is out of date.

This page is about the records you already have and the shape you want to end up with. How to find duplicate companies in the first place, including the ones that share no domain at all, is in finding duplicate companies in Attio.

How Attio stores a company's domains

Three rules from Attio's documentation decide everything else on this page.

• Domains is multi-value. The attribute (slug domains) is a multiselect. One Acme record can hold acme.com, acme.de, acme.co.uk and oldacme.io.
• Each domain is unique. A domain can sit on one company record only. Two companies can share a name; they cannot share a domain. You cannot add a custom unique attribute to Companies, so domain is the only identifier Attio enforces.
• People bring companies with them. When a person is created, Attio generates or matches their company from the domain of their email address. Someone writing from jan@acme.de is matched to the record that holds acme.de, and if no record holds it, Attio creates one.

Put the three together and the usual source of these duplicates is clear. Your team adds Acme with acme.com. Later a colleague in Munich emails from acme.de, Attio finds no record holding that domain and creates a second Acme. Nothing is broken: Attio did exactly what the data told it to.

The same rules explain why Attio's own duplicate prompt does not catch the pair. Attio detects duplicate companies by domain, and the two records share none.

Merge, add a domain, or link: which case you have

Before touching the records, decide what the second record is. The question that settles it: do you ever need to see this entity's deals, contacts or revenue on their own?

When in doubt, link rather than merge. Two linked records can still be merged later. A merged record cannot be split back into two in Attio: the merge creates a new record, and Attio's help centre documents no undo.

Case 1: one organisation, several domains

If no second record exists yet, open the company, click into Domains under the record details and add the domain. Do it for every domain you know the company uses. This is what stops the next email from acme.de creating a second Acme.

If a second record already holds the domain, Attio will not let you add it to the first: the domain is taken. Merge the two records instead. You need write access to Companies.

1. Open one of the two company records.
2. Click the ⋮ icon in the top right corner and choose Merge records.
3. Click + and search for the other record. Searching by its domain is the fastest way to the right one.
4. Put the record whose field values you trust on the right. Where both records hold a value for the same attribute, the right-hand value wins. Use the arrows between them to swap.
5. Click Merge records. Attio creates a new record from the two and marks both originals as merged.

Then open the merged record and check Domains. Attio's help centre does not say how a multi-value attribute such as Domains is combined in a merge. If a domain from either record is missing, add it now: the record that held it no longer exists, so Attio accepts it. A domain that drops off here is the one that recreates the duplicate next week.

Which record goes on the right is usually the one other things point at: the people, the open deals, the list entries. The general rules for that choice are in how to merge records in Attio.

Steps and merge behaviour per Attio's merge and delete records article and the Companies object reference, checked November 7, 2026.

Case 2: a subsidiary that stays its own record

A subsidiary you contract with separately needs its own pipeline, owner and contacts. Merging it into the parent puts its deals on the parent's record and its people on the parent's team, and your reports stop telling them apart. Keep two records and link them.

Attio has no standard parent-company attribute on Companies. You create one as a relationship attribute that points from Companies back to Companies:

1. Click your workspace name and go to Workspace settings.
2. Click Objects in the sidebar and select Companies.
3. Open the Attributes tab, create a new attribute and choose the Relationship type.
4. Select Companies on both sides. Attio allows the same object on both ends of a relationship.
5. Choose the cardinality and name each side for its role. For a simple group structure, one parent has many subsidiaries: name one side Parent company and the other Subsidiaries.

Relationship attributes are bidirectional. Set Acme Group as the parent on Acme GmbH and Acme GmbH appears under Subsidiaries on Acme Group. Creating custom relationship attributes requires Attio's Pro or Enterprise plan, and an admin or a member with full access to the object. On a plan without them, a text or select attribute such as Groupwith the parent's name lets you filter a view by group, without the clickable link.

Steps per Attio's relationship attributes article, checked November 7, 2026.

The awkward case: a subsidiary on its parent's domain

Some subsidiaries have no domain of their own. Their staff write from @acme.com, the same as the parent's. Attio cannot represent that directly, because acme.com can sit on one company only.

Pick one of two layouts and apply it the same way across the workspace:

• Domain on the parent, subsidiary without a domain. Every new person from @acme.comlands on the parent. Someone moves the subsidiary's contacts across by hand, by setting their Company attribute. Best when most contacts belong to the parent.
• Domain on the subsidiary you actually sell to. New people land where the deals are, and the parent is a record with no domain that exists to hold the relationship. Best when the parent is a holding entity you never talk to.

Either way, the record without a domain has nothing Attio can match on. Give it a clear name, such as Acme GmbH (subsidiary), so nobody creates a third one while searching, and expect duplicate scans to flag it against its sibling by name. That flag is correct: the two look alike. Skip it rather than merge it.

Rebrands and acquisitions: merge later, not never

An acquisition starts as Case 2 and often ends as Case 1. While the acquired company still renews under its own name, it is a separate customer with its own contract: link it to the new parent. When the contract, billing and contacts move to the acquirer, merge the records and keep the acquired domain on the result. Old email threads from acquired.com keep attaching to the right record because the domain is still there.

A plain rebrand skips the waiting. Same legal entity, new name and domain: merge as soon as you notice, put the record with the new name on the right so its name wins, and check both domains survived.

Finding these pairs across a whole workspace

A domain rule cannot find them. Each domain is unique in Attio, so two company records never share one, and the duplicate on acme.de looks unrelated to the record on acme.com. What they share is the name, and often the people: the same colleague filed once under each record.

In a small workspace, sort the Companies view by name and read it. Pairs like “Acme” and “Acme GmbH” sit next to each other. That stops working around a few hundred companies, and it misses pairs whose names start differently, such as “The Acme Group”. The normalisation and similarity thresholds that catch those are in fuzzy matching company names.

Deduptio does this as a scan. A company rule that keys on name finds the candidates, and each group shows why its members matched. You decide per group: merge the same-organisation pairs, skip the parent and subsidiary pairs, and skipped groups stay skipped on the next scan. Merges run through Attio's native merge, so emails, notes, tasks and list entries move to the merged record. When you pick a domain from the losing record in the review screen, it is added to the survivor's list, not swapped in for it. With cross-object matching on, a people scan treats companies you have flagged as duplicates as one company, so a person at acme.com and the same person at acme.de become comparable. That finds the duplicate people the company split created.

The limits, stated plainly. Deduptio does not know which records are subsidiaries; that decision is yours, group by group. The Free plan matches names exactly, allows 25 merges a month and scans the first 10,000 records of each object. Exact matching pairs only names that are identical after normalising case and whitespace, so “Acme” against “Acme GmbH” needs fuzzy matching. Fuzzy and cross-object matching are on Pro at $39 a month. Rollback is open for 24 hours, but it is a re-creation, not an undo: field values and associations come back, while notes, tasks, emails and list memberships stay with the merged record that the rollback deletes. Details are in match rules, rollback and plans.

Checklist for one organisation

1. Decide what the second record is: the same organisation, a subsidiary, or an acquisition still trading on its own.
2. Same organisation: merge, with the record people and deals point at on the right.
3. Open the merged record and check every domain is under Domains; add any that is missing.
4. Subsidiary: keep both, and set the parent through a Companies-to-Companies relationship attribute.
5. Check the people on each record have the Company you expect, especially when two entities share one domain.

Related

• Finding duplicate companies in Attio — match rules for the duplicates that share no domain at all.
• Fuzzy matching company names— why “Acme” and “Acme GmbH” match and “Acme Health” does not.
• How to merge records in Attio · Undoing a merge · The full guide