Ferd is a puppy and playing. She is not misbehaving and it's OK to leave her. Leave Ferd in the ex-pen with toys and install a different potty tray. Puppies play with anything that isn't tied down. Use the crate at night or for an established nap time.
You will be able to housebreak Ferd very quickly if you use a potty tray. But, you must also keep her confined, if you don't have eyes on her and do not give her Free Rein around a room until you're confident she will go to the potty tray. Train her one room in the house at a time.
I've tried almost every potty training tray type made including Fake Grass Turf. I didn't like the Fake Grass Turf because it smells. You can wash it but the more the puppy pees and poops on it the harder it is to get the odor out.
I have not tried Real Grass. However, I would think it will smell after the puppy pees and poops on it numerous times. And... Ferd will probably play with the grass, too.
This is what I found that works. The UgoDog.net (Company does not sell on Amazon) or the Byliss Klean Paws Potty Tray (Sold on Amazon.com) are my favorites. You can get potty trays with sides that helps keep the puppy inside the tray. If I had a do over - I would try that tray.
You want a trays that clamp down over a paper potty pad or pellets that are put inside the trays. (The trays I've suggested have enough room for equine horse pellets.)
With this type of set up a small breed puppy will NOT get into the tray and tear up the paper. Easy clean up. With a small puppy you'll probably need to change out the pad every other day, may every third day. The poop is on top of the tray. Pick it up and throw it away in the stool. As the dog gets older and bigger you'll have to change the paper pad out every day or twice a day because of the odor.
Another option is to use Equine Horse Pellets inside the potty trays. Several of us on the forum prefer the Equine Horse Pellets to paper potty pads, because the pads have an odor. The Equine Horse Pellets are used for horse bedding and has no odor when peed on. As an analogy ... It works like Kitty Litter in dog potty trays.
The Equine Horse Pellets don't have to be changed as often because there's no odor. Just throw it away and put new pellets in the tray. You can buy Equine Horse Pellets at Tractor or Farm stores. It's about $5 for a 40lb bag.