[{"item":{"some":"data 123"},"owner":{"id":456},status:{ok:1}}]

db.collection.aggregate([{$facet:{new:[{$limit:1},{$replaceRoot:{newRoot:{item:{some:"data 123"},owner:{id:456}}}}],old:[{$match:{"owner.id":456,status:{$exists:true}}}]},},{$replaceRoot:{newRoot:{$mergeObjects:[{$arrayElemAt:["$new",0]},{$cond:[{$ne:[{$arrayElemAt:["$old",0]},null]},{status:{$getField:{field:"status",input:{$arrayElemAt:["$old",0]}}}},{}]}]}}},{$merge:{into:"collection",whenNotMatched:"insert"}}])