Exactly - and I think this is one area that hasn't been discussed much. Rules are pretty clear that paying for more than one seat doesn't earn more miles into the same FF account. Thus it makes no difference whether you paid for a second seat for your cello, a dog, a kid or even half of your body - you just can't rake the miles.

But if the second seat is a different FF account, then IMHO that's a very different story. This is not any different than a newborn flying in its own fully paid-for seat (and with his own FF account): a "guardian" normally pays for the tickets, the two pax are put on the same PNR (which could even hit negatively upgrade chances), etc.

Sure, the legal guardian can then give or transfer the miles later on, under some specific conditions (and, depending of the FF program, with significant fees). But then again, it's not any different than for any parent flying with a newborn. I don't see what the fuss is all about - unless the rule now is that FF accounts are only provided to humans. That's quite different than saying both seats yields miles into a single account.