Dear judith MP,
Good day! Thanks for querying in this forum. We’re happy to help you.
From your description, it seems that you want to skip the authentication prompt when user try to access the inserted link to a SharePoint list in the second tenant in Access database.
Based on the word you mentioned" pick up a verification code to access this data", may I know if you have set MFA on the second tenant? If so, we'd recommend you share second tenant B's list with tenant A user account, configure cross-tenant access settings to trust MFA, and/ or create a Conditional Access policy to control the sign in frequency or exclude trusted accounts as a workaround.
For your reference: Configure authentication session management - Azure Active Directory - Microsoft Entra | Microsoft Learn
Require MFA for all users with Conditional Access - Azure Active Directory - Microsoft Entra | Microsoft Learn
Hope above information can help!
For the VBA code, we would love to help you on your query about VBA code, however, our team focuses on general query, for example, installation and activation issue of Office 365 products. For the situation you mentioned related to VBA code, you can refer to this article: Office VBA support and feedback | Microsoft Docs to go to Stack Overflow by using the VBA tag, along with any other relevant tags as there are also many experienced engineers and experts in the forums there.
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At the same time, we will also keep this thread open, so other Community members and Experts can also share their suggestions and inputs.
If the scenario above is not consistent with yours, you can also post back and point that.
Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!
Thank you for your cooperation and understanding!
Sincerely,
Rhoda | Microsoft Community Moderator