How do I use flow to stack up metafield instead of overwriting

Shopify Plus
1

Hi,

We would like to set a flow to add metafield to a product, instead of overwriting we would like them to stack up, below is the flow I set:

ChingLau_2-1708589358995.png
ChingLau_2-1708589358995.png1598×595 82.7 KB

Below is the second update product metafield section:

ChingLau_3-1708589430034.png
ChingLau_3-1708589430034.png1572×609 84 KB

Eventually we will have >200 different metafields to be added to >10,000 products

Each product will likely have 3-4 metafields with different combinations.

Any help is greately appreciated.

Thanks,

Ching