(Deprecated) Create a split transaction

In our efforts to improve our Nexus API, we have implemented newer, better endpoints to create and delete split transactions. As such, this endpoint has been deprecated, but it remains documented for previous integrations using this feature. All new integrations must use the improved split and delete transaction endpoints. This endpoint creates a new transaction that is branched from a previous transaction, allowing you to link multiple categories, descriptions, amounts, and additional information to a parent transaction. When a split transaction is created, the parent transaction's has_been_split field will automatically be updated to true, and the split transaction's parent_guid will have the transaction guid of the parent.