Musical performances and singing as an auto-entrepreneur?

It seems you cannot declare a musical performance as part of your auto-entrepreneur activity for the month - does this apply even if musical performance is not your primary activity? I am a translator, but will be doing the odd paid concert. Is it really impossible to be an independent musican? I have a performing musician friend who declares performances under the auto-entrepreneur system, and was apparently advised that she could do so. Also, the Cheque-Intermittents site you posted in another thread seems to be a private company charging 7,5% for their services. Am I right? In this case wouldn’t it be better to register with the Guichet Unique (GUSO)?

I am starting to sing as part of a group of musicians who are currently debating how to declare earnings for playing at a wedding or corporate event. There is the possibility of playing in the UK and I had assumed that I could declare my earnings from the UK gig on my French auto-entrepreneur declaration for that month. If that is not possible, would I need to register on the GUSO for myself on my own behalf? There would be no way to persuade the UK organiser to register on the GUSO, in practice… so how to declare that income?

Or, when playing a paid gig with a band, can I employ the other musicians in the band (even if I were not the organiser in reality) and take an administration charge in lieu of my own performance fee - since I could not employ myself for the performance?