An unloader valve can be installed to overcome that obstacle.
This nifty device is also called a capacity control valve. It is a three-port solenoid valve. It has many uses, but in this situation, it connects the discharge and suction pipes of the compressor group to each other. It has a check valve at its outlet (or merely closes the discharge port when unloading occurs), so that the high-pressure refrigerant built up in the rest of the system cannot rush backwards into the suction side.
When another compressor in the group is called into action, the unloader valve is energized, and the pressure across the compressor group equalizes at suction pressure. The extra compressor is started while the running compressor group is unloaded as well, so there is no excessive electrical load generated. All of the running compressors draw minimum current, and the summoned compressor starts easily. Once the extra compressor is online, the valve is de-energized and the refrigeration cycle starts doing its job again. In most cases, this operation happens so fast that the pressure built up in the condenser doesn't have time to bleed off.