Using a substitute on my Delivery apps-are the earnings I forward to substitute an expense?

Hi I am currently working as a self employed sole trader delivery driver on the main delivery apps (Just eat Deliveroo Amazon Flex GoPuff Uber), these apps allow me to use a substitute to deliver for them when I want to. My wife has recently started using my delivery accounts on these apps to also deliver part time and work, she has registered self employed also. As the apps are all in my name the earnings are paid directly to my bank, I am forwarding any earnings made by my subtitute directly to her account, when it comes to Self assessment I assume I would total up the earnings on the apps and then minus my costs, these costs would also include any earnings that I have forwarded to the substitute and then I would pay tax on the profits. I assume the substitute would then complete her self assessment and input the earnings forwarded to her from me minus her costs and then pay tax seperately on the profits. Am I correct in these assumptions or does it work differently for self assessment? Can't seem to find any tax information relevant to substitute delivery drivers online.

Hi,

Yes, you are correct.

Thank you.