Answer
Yes, but it isn't a simple single API-task call — it requires reproducing the Assistant's own virtual-set mechanics: one task creates the pre-accounting virtual set and prepares the next step, a following task reads the nested pre-accounting array as its own entity, and a final task inserts the actual values into that array. It's a more involved workflow than a typical single-entity update, and the client debugger doesn't always make the virtual-set behavior obvious, but it does reproduce what the Assistant does.