An endpoint is needed to retrieve underlying information about a split deal.
For example, from the deals object - I am able to return hs_is_deal_split = "true" and hs_num_associated_deal_splits: 2; but I need to know that owner id 1 gets 25% and owner id 2 gets 75% so that commissions can be calculated accurately. I asked this question in the API/Integration Community and it appears that this information is not currently able to be retrieved.