It is impossible for an outsider to 'steal' rewards if you don't leave them lying around where people can steal them! In other words, if your fellowship has one or other decent swap system, this can never happen - on ours, for example, the top contributors to the swap thread have made contributions like this example:
View attachment 6167
So it is impossible for an outsider to sneak in and steal a 'cheap reward' if you have a good swap system.
One should NEVER donate points to your own Ancient Wonder - for two simple reasons:
1. Taking a wonder to within 100 points of completion before offering it to your friends, opens the door for so-called 'KP pirates'.
2. More importantly, a knowledge point you swap with a friend has a chance of helping you to get bonus KP and rune shards. If you drop it in your own wonder, it has zero chance of gaining you anything. That is why I drop every single KP I have into swaps of various sorts, on a daily basis - and average between 10 and 15% extra bonus KP as a result.