Many growers especially have 5 - 6 phal seedlings in a compot. And as the plants grow over the years they just keep repotting the entire compot into larger and larger pots until the seedlings flower and the best are selected. So, yes, you can certainly grow more than one phal in one pot. This pot has four plants in it, Doritis pulcherrima 'Lemon Dolly'.
I see no reason why you can't grow phals 'grouped'. They certainly grow that way in nature. I'm trying two in one pot at the moment at they are doing fine.
AL