And for Golds even if they're on a different PNR, although you have to phone for this.

I have never seen anything to indicate the extra baggage allowances extend to travel compantions. But I can hardly see this being an issue very often. One bag (plus a very generous hand baggage allowance) is normally enough in short haul. And do Silvers/Golds travel very much in WT? Even in WTP don't you get two bags, which is enough for most people?

When I'm going longhaul, I'm pretty borderline between one and two bags. If by some horrid accident I was stuck in WT with a Blue companion, I'm sure my 2x32kg allowance together with his 1x23kg allowance would be enough between us, unless it's a really big trip like actually moving abroad for a year.