Originally Posted by UKtravelbear

The UK Government won't care that you will lose a deposit.

You MUST comply with UK Immigration law which is quite clear in the circumstances you have outlined, Trying to get around them won't help you and will more then likely prevent the artiste being able to enter the UK in the future.

Contact a UK immigration lawyer or one of the venues you propose the artiste will perform in for advice - they may be able to act as a sponsor and have probably done this sort of thing before

I assume you have a Swedish lawyer - talk to them.

Honestly asking for detailed immigration advice on an internet website is not not the way I'd expect a professional company to behave.