15 year old son selling on whatnot - tax implications

Un parent demande des conseils sur les implications fiscales liées aux ventes en ligne de son fils mineur et comment gérer les paiements pour éviter des problèmes avec le fisc.

Hello, my partners 15 year old has started selling trainers in whatnot. I went through their terms and conditions and set the account up under my details as advised. He's done a few shows and it's time to start his payout and it obviously needs a parent's bank account. The issue is that he's doing really well and in about 3 weeks has £2k to cash out. He needs the money to go get more stock from the outlet malls. My question is how do I do all this legally so I don't get HMRC chasing me for money. My annual salary is somewhere around 56k and my partners is 18k. Would there be benefits to it going to her account instead of mine? He does have his own account but as per terms and conditions the payouts need to go to a parent. He's joing the RAF in September under a apprenticeship but will hopefully continue to sell part time. Any more info people need just shout.