Forex Profit sharing while compounding

Hey guys
So Im sure not many threads out there with this topic since everyone is still trying to make money but I was wondering about this. How does one calculate profit sharing with compounding? Heres the scenario. I have someone whose trading for me, lets say we decide on 80:20 split. I am interested in compounding, so lets say we start with $1000. We do profit sharing weekly so lets say he makes $50 the first week. So at 8020, that's $40 for me, $10 for him. Now lets say, I don't take my share and give him his $10. Now the balance is 1040 when it shouldva been 1000 but I didn't take my share. So now we split profits on 1040 and so on, so Im basically giving him more from my cut, make sense? Like im trying to figure out how can it stay even, well I guess the only way is we keep taking our profits and balance remains at $1000. If someone has any idea, would love to hear about it, thanks

Source.