Books in the Wally & Chrissy series in order

Penny has two cats. Wally and Chrissy. Which one did she get first?

Penny has bought a bush. Now she has to dig a hole for it. Can she plant the bush in the hole?

It is Saturday. Penny has the day off. She wants to sleep in. Will Wally and Chrissy let her sleep?

Wally has a present for Penny. It is a dead mouse. Will Penny like her present?

It is dinnertime for Penny’s cats. Chrissy is already here. But where is Wally?

Chrissy has eaten a ribbon. Eating ribbons is dangerous. Is Chrissy going to die?