Adding Products during an Process Cash Adjustment

Hello.

I have been reading up on Persisted Cash in order to handle some invoice adjustments. I'm familiar with the conversation here: https://developer.imis.com/discuss/68f030605c59a8da479e8b74

I'm looking to perform a Process Cash Adjustment POST to the /api/Invoice/_execute endpoint as described here:
https://developer.imis.com/reference/executeinvoice-1#processcashadjustment

My adjustment has two parts:

Removal of some line items (which I know I can accomplish through the handy IsRemoved property laid out in the discussion I linked above).
Addition of one or more new line items (as replacement for the removed products).

Its that second part that I'd like some help on. What structure should my request take in order to add a product code to the invoice? Are there any properties or configuration details that are of interest in performing this sort of operation that I should be aware of when setting up my calls?