Pip and Posy: The New Friend by Axel Scheffler
Pip and Posy are having a lovely day at the seaside, collecting shells and digging the sand. But when Posy has a nap, Pip makes friends with a boy called Zac. Zac is very cool: he has lots of fun toys and beach gear, AND he's really good at handstands. So, to her dismay, when Posy wakes up, she finds that Pip is more interested in playing with Zac than her. A funny and dramatic story about working out that two's company and three's a... PARTY!