XSA - OData - Merge vs Put - ".update" function ISSUE

Hi, I'm migrating from XSC to XSA (Cloud), and running into an issue with my oDataModels where I typically write ".update", but seeing as "MERGE" is not supported, what is the recommended work around? If I were to use "PUT" this by definition would replace the row with my payload, but I only want to change the "Deltas".

Another solution is to write a procedure, but this is very challenging as I'd have to do this for every table definitions, meaning quite a bit of work + very challenging to manage the procedure and any table updates.

Can you advise on the workaround?