Step 7.2. Override using GA4 tag

In this case you will need to manually configure each Facebook CAPI tag in server GTM. We will show add_to_cart event as an example, the configuration of other events are similar. 

1. Open server GTM container and add FB CAPI tag template from the template gallery. 

2. Create a new tag with the tag type Facebook Conversion API → select override in the Event Name Setup Method and add:

• FB API Access Token. 
• FB Pixel ID.
• Test ID. 
• Choose an event name from the standard events list or create a custom event name. For example, I chose the AddToCart event.
• Go to the Server Event Data Override section and choose "Event ID" for the Property Name. Then, in the Property Value field, add the {{event_id}} variable that was created in step 6.
• Inside User Data section and Custom Data you can add any user or product data you want to send to Meta. 

3. Add a trigger. In our case it is a Custom event with the event name add_to_cart and a client name equals GA4. Click Save.