MOSFETS are generally described as easy to parallel. Unlike diodes, they do not go into thermal runaway.
The MOSFETs I have been using, IRF540PbF are described in the datasheet as "Ease of Paralleling". This is not mentioned in the Datasheet for the latest MOSFETs I am using, IRFB4410ZPbF, or some others I am interested in trying IRFP3206PbF which is a much heavier package.
However I have not been able to locate any information on paralleling High Side MOSFETs. The datasheet for the IR2103 MOSFET driver I am using states "The floating channel can be used to drive AN N-channel power MOSFET or IGBT in the high side configuration which operates up to 600 volts".
I have therefore been paralleling the drivers instead. One driver for each MOSFET pair. The HCPL2200 Opto coupler is capable of handling up to 4 TTL fanout. Seems to work so far. A downside I have found is that if the driver low side input to one set of MOSFETS gets disconnected then there is a shortcircuit created. This is because the driver low side output goes high and turns the MOSFET on. This can easily be fixed by changing to the IR2101 driver which does not have an inverting low side input, and change the PWM NAND gate to an AND gate. I now use only the IR2101 and any reference to the use of the IR2103 in these pages should be disregarded.
I think parallel coil windings, using multiple MOSFET bridges may be an easier way to go.