Don't be silly.
If you are using the devices purely as switches, the situation does get more complicated.
The static current distribution is then determined entirely by the "on" channel resistance, and while - as Forsythe says - you still have to take into account the worst case tolerance range in the on channel resistance, at least you can rely on a positive temperature coefficient to avoid a bad distribution getting worse.
The data sheet for the Fairchild parts you nominated doesn't specify a worst case minimum "on" resistance; the typical to worst case maximum ratio is close to 3:4 so one might hope for a minimum to maximum ratio of 2:1 which isn't too good.
The dynamic current distribution - while the switches are turning on and off - does depend on the gate threshold vvoltage, with most of the current concentrating on the part with the lowest threshold voltage when the devices turn on and turn off. The switches don't spend all that long a time switching on and off, but a lot of power gets dissipated in the junctions while this is going on - I used to select switching frequencies such that the static and dynamic power dissipations in the switches were more or less the same, but if I'd been under pressure to minimise the size and cost of the components doing the output filtering I'd have probably set the swithing frequencies rather higher.
-- Bill Sloman, Nijmegen