sub account

The game is Plants vs Zombies GW2. Can PS 4 Playstation Plus Members and there sub accounts have access to online play? Or do they need their own Playstation Plus Memberships? My kids are 8.  I have two consoles and two games so I can play online with them in split screen mode. 

News and Media quote from Plants vs Zombies GW2 site:

What are the multiplayer options?

There is up to 24-player online multiplayer and up to 4-player online co-op. Or if you prefer to play with friends locally, you can play with or against a friend in split screen across every mode on Xbox One and PS4. That’s right – from the comfort of your own couch you and a friend can enjoy every mode of the game in split screen, and even play on opposing sides! You will be able to play co-operatively with a friend online, but it will not be split screen.