Update about-billing-for-github-copilot.md

Author: holly-kassel

content/billing/managing-billing-for-your-products/managing-billing-for-github-copilot/about-billing-for-github-copilot.md

@@ -26,6 +26,22 @@ Subscriptions to {% data variables.product.prodname_copilot_pro %} are available
 
 If you want to try {% data variables.product.prodname_copilot_short %} before subscribing, you can use {% data variables.product.prodname_copilot_free %} for a limited experience. See [AUTOTITLE](/copilot/managing-copilot/managing-copilot-as-an-individual-subscriber/about-github-copilot-free).
 
+## Migrating between Copilot plans
+
+When transitioning between different GitHub Copilot plans, you may encounter situations that require support from us. 
+
+### Migrations requiring support assistance
+
+Some migrations cannot be completed through self-service options:
+
+- **Non-GHE to GHE environment migrations**: When moving from standalone Copilot subscriptions to a GitHub Enterprise environment, contact GitHub Support or your account manager for assistance to avoid service interruption or double billing.  
+    
+- **Changing between Copilot for Business and Copilot Enterprise**: If you need to migrate between these plans within your enterprise and the option isn't available in your Billing & Licensing settings, contact GitHub Support or your account manager for assistance.
+
+### Trial expiration notices
+
+If you're seeing an expired trial notice despite having an active paid subscription, this display issue doesn't affect your current paid access. If this persists, contact [GitHub Support](https://support.github.com) for assistance.
+
 ## Further reading
 
 * [AUTOTITLE](/copilot/about-github-copilot/subscription-plans-for-github-copilot)