Yes, you can post your trip on other carpooling platforms as long as you clearly state in the trip description that you may have other passengers in the car.
Best practices when posting on more than one platform:
Avoid overbooking: Be careful not to accept more passengers than your car can comfortably accommodate.
Double-check passenger details: On the day of travel, verify that the passengers getting into your car match the names listed on Poparide. This ensures you’re picking up the right people.