conversion of RS6 to 7 seats



Hi there
New to this site. I currently drive a volvo v70r awd and am looking to change but having 4 kids I want a high performance car that can seat 6/7.
Was originally looking at a used Merc E55 estate but I like 4 wheel drive and would like to look at the RS6 if I can get it converted.
Does anyone know if the dealers can do this or if there is a company out there that are able to do it.
Many thanks