Can we transfer the stuff we have from one acc to another?

I have a little brother who wanted me to farm ip on his account because he cant play much so I did but now he doesn't want to play league anymore and I have a lot of time investment in his account and the champions on there. I have a lot of champs on the account I was farming for him on that I don't have on my current and I was wondering if I could transfer it over because I don't want to have to switch accounts to play certain champs since my brother refuses to play league now (he is only 6 anyways) and I still worked to get those champs. I don't even care if I have the masteries for them still. If there is a way I could transfer it over let me know. Thank you it is appreciated