Dual Boot Win 7 and Win10

Apologies if this is 'old hat'. I'm having trouble with win 10 (getting wifi working) and have a thread specifically on that subject already open. I'm in the position of installing win10 on my son's laptop and soon have to give it to him - but he lives 80 miles away. Win10 does not work in terms of wifi on this laptop but wifi does with win 7 so how can I resolve this win10 issue when I do no have the laptop? I can remotely access the laptop so is there an option of giving him back the laptop in a dual booting mode using win7 and win10? The win10 install licence is derived from the win7 key so what would the situation be if both OSs were install of the same machine - would it work?

In my opinion based on my limited understanding................... your Win 10 will NOT get activated on the dual boot setup.
It is because your Win 7 is on the computer and its product key is considered " in use".
You cannot use the same key to activated another OS installation even it is installed in the same computer.

That said, I remember distinctly during the Windows Technical Preview era, I had a Win 7 Home Premium laptop which I setup a partition and installed the Preview into it. And it got activated automatically.

So, heck, I can be wrong completely.