Many organisations want Copilot to consistently use a specific website or data source. It might be a regulatory portal, a fund information site, a research provider or a trusted industry reference. The question is straightforward: can Copilot be told to “always check this site first”?
The answer depends entirely on which Copilot experience you are using. Some versions of Copilot cannot be customised at all. Others can be guided, but only within a session. SharePoint and Cowork offer more flexibility, but with important limitations. Copilot Studio provides the most robust and predictable solution.
This article explains the capabilities and limitations across Copilot Chat, Microsoft 365 Copilot Chat, the Word, Excel, PowerPoint and Outlook Copilots, SharePoint and Copilot Cowork. It also clarifies what Copilot’s memory feature can and cannot do in this context. Finally, it outlines the approaches that do work.
Copilot Chat (Web and Windows)
Copilot Chat is the general chat experience available to consumers and business users. It uses Microsoft’s grounding pipeline and public web search. It cannot be configured to prioritise a specific website.
What memory can do
Memory can store personal preferences such as writing style, tone, preferred formats and recurring tasks.
What memory cannot do
- Store search preferences
- Enforce grounding rules
- Prioritise external websites
- Override Microsoft’s search ranking
Even if you store a preference such as “I use website X frequently”, Copilot will not treat it as a grounding rule.
A useful way to think about memory is that it can influence how Copilot responds, but not where Copilot retrieves information from.
Verdict: Copilot Chat cannot be grounded in a preferred website, and memory does not change this.
Microsoft 365 Copilot Chat
Microsoft 365 Copilot Chat behaves similarly. It grounds itself primarily in Microsoft 365 tenant data and can also use other approved grounding sources such as web grounding when enabled by administrators.
What memory can do
Memory can store personal working preferences, such as preferred formats, terminology and response styles.
What memory cannot do
- Store grounding rules
- Prioritise external websites
- Override enterprise search ranking
Tenant data is prioritised automatically, but external websites cannot be promoted to a preferred source.
An important nuance
Microsoft has introduced controls that allow administrators to exclude specific domains from web grounding. This provides some influence over which websites Copilot can use, but it still does not allow administrators or users to specify a preferred website that should always be searched first.
Verdict: Microsoft 365 Copilot Chat cannot be grounded in a preferred website, and memory cannot be used to achieve this.
Copilot in Word, Excel, PowerPoint and Outlook
The Copilot experiences inside Word, Excel, PowerPoint and Outlook are designed to work with the content in the document, workbook, presentation or mailbox. They do not support custom grounding or external website prioritisation.
What memory can do
Memory can store preferences such as tone, formatting style and response structure.
What memory cannot do
- Influence grounding
- Prioritise external websites
- Change how Copilot retrieves information
These Copilots primarily work with the content provided, together with Microsoft 365 data available to the user.
Verdict: The Office app Copilots cannot be grounded in a preferred website, and memory cannot change this.
SharePoint and Grounding
SharePoint is the first place where grounding becomes more flexible. Copilot in SharePoint prioritises content stored within your tenant and respects existing permissions.
If you can mirror or import content from a preferred external website into SharePoint, Copilot can treat that content as authoritative tenant content.
However, importing external websites into SharePoint is generally unwise. It introduces maintenance overhead, versioning concerns and compliance risks. Most organisations will not want to maintain a parallel copy of an external web resource.
SKILL.md in SharePoint
SharePoint supports SKILL.md files that allow organisations to create reusable workflows and repeatable processes.
Skills can:
- Define workflows
- Structure tasks
- Guide Copilot behaviour
- Automate repeatable multi-step activities
- Reference SharePoint content
Skills can strongly influence how Copilot performs a task, but they cannot directly change the underlying search or grounding mechanisms.
Skills cannot:
- Force Copilot to use an external website
- Change search priority
- Make Copilot treat an external website as authoritative
SHAREPOINT.md
Modern SharePoint AI experiences can also use site-level context files such as SHAREPOINT.md. These files provide persistent organisational context, business rules, terminology and site-specific guidance.
SHAREPOINT.md can help shape responses and improve consistency, but it cannot override grounding or redirect searches to an external website.
Verdict: SharePoint grounding works only for tenant content. SKILL.md and SHAREPOINT.md can guide behaviour but cannot make Copilot prioritise an external website.
Custom Agents
Between standard Copilot experiences and full Copilot Studio development sits a growing category of custom agents.
Custom agents can be configured with:
- Specific instructions
- Knowledge sources
- Scoped content
- Bespoke behaviours
They provide more control than standard Copilot experiences and can focus responses on specific repositories or business knowledge.
However, they still do not generally provide the same level of control over external website prioritisation as a dedicated Copilot Studio implementation.
Verdict: Custom agents can narrow and focus grounding but are not a general-purpose solution for enforcing a preferred public website.
Copilot Cowork (Consumption Model)
Copilot Cowork is the only Microsoft 365 Copilot experience that supports custom skills and structured workflows. Cowork now operates on a consumption model.
Cowork allows:
- SKILL.md files
- Custom workflows
- Trigger phrases
- Multi-step logic
- Persistent context within a task
You can instruct Cowork to:
- Use a specific website as the primary reference for a task
- Ground outputs in a dataset
- Treat a SharePoint library as authoritative
However, this grounding only persists inside the Cowork task. It is not global across all Copilot experiences.
Memory in Cowork
Cowork does not use Copilot Chat memory. It relies on skills, instructions and task context instead.
Skills can reference a preferred website, but only within the scope of the Cowork workflow.
Verdict: Cowork can use a preferred website, but only within a Cowork task.
Solutions That Do Work
Copilot Studio Agents
If you need Copilot to consistently use a specific website, API or data source, Copilot Studio provides the most robust solution.
A Studio agent can:
- Call your preferred website or API
- Use dedicated website knowledge sources
- Parse and structure data
- Provide consistent behaviour
- Be invoked from multiple Copilot entry points
Copilot Studio supports public website knowledge sources, SharePoint knowledge sources and a broad range of enterprise data sources.
Best for: Organisation-wide consistency and custom data sources.
SharePoint Grounding
If website content can be mirrored safely into SharePoint, Copilot will treat it as tenant content and prioritise it accordingly.
This is most suitable for static or semi-static content.
Best for: Controlled content repositories.
Custom Agents
Custom agents provide a middle ground between standard Copilot and full Copilot Studio implementations.
They can focus Copilot on particular knowledge sources and business contexts but are less flexible than Studio agents.
Best for: Departmental solutions and focused business knowledge.
Copilot Cowork Skills
Cowork skills allow you to define workflows that use a preferred website or dataset for specific tasks.
Best for: Project-based and task-oriented work.
Which Approach Should You Use?
| Copilot experience | Can it use a preferred website? | Does memory help? | Notes |
|---|---|---|---|
| Copilot Chat | No | No | Memory cannot store grounding rules |
| Microsoft 365 Copilot Chat | No | No | Website priority cannot be customised |
| Word, Excel, PowerPoint, Outlook | No | No | Focused on document and tenant content |
| SharePoint | Yes, indirectly | No | Content must exist inside the tenant |
| Custom agents | Partially | No | Can narrow knowledge sources |
| Copilot Cowork | Yes, within tasks | No | Skills and workflows |
| Copilot Studio agent | Yes, fully | Not applicable | Most predictable solution |
Final Guidance
If your goal is to make Copilot consistently use a specific website, the most reliable approach is a Copilot Studio agent with that website configured as a knowledge source.
If you only need grounding inside a specific project or workflow, Copilot Cowork may be sufficient.
If the site’s content can safely be copied into your Microsoft 365 tenant, SharePoint provides an alternative grounding mechanism.
Memory, SKILL.md files and SHAREPOINT.md files can all influence behaviour and improve consistency, but none of them can force Copilot to prioritise an external website.
Novia Works Ltd 