Stolen bike returned

Can you change and update your belongings that are registered on immobilise.com? I'm always swapping parts, changing frames etc. so I would need to be able to change parts of the registration.
Also, couldn't a theif steal the bike (or whatever they want) and then register it as their own?

**From the immobilise website: **If the items are not already recorded with us, simply create and account and add the item, then report it as stolen or lost.