Do they have Disney APs? Otherwise they'll have to pay for Disney parking as well as RPH parking.
Does their rate at the RPH require a 7 night stay? One option is to stay at RPH for 4 nights and at WDW for 3 nights. They could try to get one of the All Star Family Suites or 2 rooms at a value. They'd use a car service to go from MCO to RPH and from RPH to WDW. They'd use DME to get back to MCO. That would save renting a car. That would also give them EMH. Probably the best option. Gives them the opportunity to take an afternoon break.
Price a rental car for the entire week. Including the cost to park at the RPH and at WDW. I guess they could also price a 3 day rental. Pickup at RPH with a return at MCO. They'd still need a one day rental (or car service) to get from MCO to RPH.
Even when you include the parking charges a weekly rate will probably be a better deal. The cost for a car service to go from MCO to RPH will be around $60. A one way car rental won't be that much cheaper. That basically pays for parking at RPH for the days you won't need a rental car.
Are they under a
budget? Taking a taxi from RPH to WDW will save renting a car and paying for parking. Mears taxi estimator suggests the fare from Universal to EPCOT is around $32. A car service will cost $60-$80 R/T. Spending $200-$300 on taxis is likely to be more expensive then renting a car but less hassle.
JMO but either staying at WDW for 3 nights or renting a car for the entire week is likely to be the easiest solution.
edited to add the restaurants at the RPH aren't cheap. They could easily save more then the $20 parking charge if they use the car to have a couple of meals offsite.