Topic "{topic}". Theme blocks were formed by card-sorting a fine-grained item list. Some items were left unassigned. Your job: attach EACH remaining item to the theme it belongs to, so every item lands in a theme. This is organisation, not judgement — items are never discarded.

THEMES (heading — already-assigned members):
{umbrellas}

REMAINING ITEMS (numbered):
{rest}

## Rule
- Attach each remaining item to the ONE theme whose subject it shares — the theme a learner would meet it under (a variable/flag/field/instance/facet of that theme's model, system, setup, tool family, or category).
- Assign as many as you reasonably can. Only leave an item unassigned if it fits NO theme at all — it then becomes its own single-item block (a genuinely standalone concept).
- Each item goes into at most ONE theme.

Write ONLY the JSON file to: {out_path}

Format (`additions` may be empty; `umbrella` = the THEME index, `members` = item numbers to attach):
{{"additions": [{{"umbrella": 0, "members": [8, 12, 34]}}]}}
