Incremental Refresh and dataflows to save historic data

Hi All,
I'm trying to use dataflows and incremental refresh to get and save data from an external API.

I've created a dataflow (A) where I'm accessing the API to pull the most recent data, this dataflow is refreshed once a week.
I've created another dataflow (B) using dataflow A as it’s source, and set up incremental refresh to refresh data from the past 2 days and keep data for 16 months. This refresh occurs once a week, on the following day to dataflow A's refresh.

The problem is: data flow B keeps being overwritten with the most recent data a from dataflow A, the previous data is not saved at all.

I'm not sure why this doesn't work, maybe it's related to dataflow A being a 'linked entity' in dataflow B, and then referenced?

I have Incremental refresh working in a completely different dataflow, so I thought I had it figured out, obviously I was wrong 🙂

Should this work? not sure if there is something I'm missing in setting up these dataflows, or if I need to completely change my approach?

Thank you for your help!