Missing install disk for a game but have all game play disks

[imptastick2]

My brother picked up a used copy of Baldur's Gate for PC from goodwill, but he called me and said that all the disks are there except the install disk. He is extremely anti-piracy and is refusing to just download the game; is there anyway to install the game and then run the rest off of the game disks, as if he had installed off of the disk?

[audun]

After paying for the game he has all rights to download the game.

EDIT:
Otherwise if he picked it up in a store, can't he just go back and claim for a new copy?

[imptastick2]

[QUOTE=audun;38878795]After paying for the game he has all rights to download the game.[/QUOTE]

I have been trying to explain that, I may just go ahead and download and .iso and not tell him

[editline]18th December 2012[/editline]

[QUOTE=audun;38878795]
EDIT:
Otherwise if he picked it up in a store, can't he just go back and claim for a new copy?[/QUOTE]

Goodwill is like a thrift store, they have a bunch of stuff really cheap but it is all as is, no returns or refunds.