Various configuration of linear regulator for parallel operation discussed in this technical article from Analog Devices. Link here
Linear regulators provide a simple, low noise solution for dc-dc regulation. However, at higher VIN-VOUT differentials the low efficiency and high power dissipation of linear regulators limits the amount of output current that can realistically be delivered. Connecting multiple linear regulators in parallel spreads the load (and the heat) over several ICs, increasing the useful range of output currents a solution can deliver. However, connecting linear regulators in parallel is not always straightforward.
from Dangerous Prototypes https://ift.tt/2S4Lf0o