Yes, additional ones can be used. It is impossible not to use their exchanger, if only because everything is protected there as much as possible. You can really trust this exchanger. I have verified this from personal experience.
It really is. Like you, I consider this exchanger the safest of all anonymous exchangers. After all, there are anonymous exchangers that can steal your data or something like that, but this does not apply to the Crypton exchanger.