Append a Dataset using Domo API

We are trying to append data to a dataset using the "Import data into DataSet" DataSet API Platform(OAuthAPI) documentation. https://developer.domo.com/portal/4ba1c85b30ae1-import-data-into-data-set

When we use end point "https://api.domo.com/v1/datasets/{dataset_id}/data?updateMethod=APPEND", it replaces the data in the dataset. I think this is by design.

Is there another endpoint that I should use to append a dataset?