Thanks for your thanks, BigV!
I'm not confrontational by nature and find it difficult to give them words of 'discouragement'. However, they did catch me off guard one day and I eventually told them, in somewhat forceful terms, that what they were proposing was fraud and I wasn't going to be party to a criminal conspiracy. It made me feel a little better, but not for long.
I have yet to 'go nuclear' but I'm conscious of the fact that it would probably have a negative effect on my sense of well being if I told them that they might like to indulge their interest in sex and travel, so to speak.
All the best,
Carruthers