Cautiously ski green runs IMHO is not ready for the Pano lift first day. When I used to instruct, the worst thing you could do was to over-terrain a kid. Really sets them back.
If the beginner and dad are skiers, then they could conceivably ski down the catwalk to the WP side which is a green all the way. Snowboarders will not like it.
So you may want start at the WP side after all and follow Magi's advice. Drop off the kids and one dad with all the gear and then go park.
You can pay for the garage parking at WP village, but it is still a pretty long walk through the "village" and past the shops and restaurants to get to the balcony house to pick up passes etc. They have red wagons for shuttling gear, but for first day at altitude it may not be the best way to start the kids off. And, the children's ski school is yet further away at the very other end of the complex from the garage. It is, frankly, the one thing I think they screwed up at Winter Park. Not smart to have parents and kids schlep for what seems like a half a mile from parking to ski school. Makes the shuttle from the parking lots more appealing than paying to park and walking.