Royal Cousins Mia Tindall, Savannah and Isla Phillips Are 'Very Taken' with Baby Lena on Playdate

Before Meghan Markle and Prince Harry add another member to the exclusive club of Queen Elizabeth‘s great-grandchildren, several of the royal cousins had a special playdate!

Zara Tindall competed in the Gatcombe Park Horse Trials over the weekend, and many members of the royal family stepped out to cheer her on. It turned into a weekend-long playdate for cousins Mia Tindall, 5, Savannah Phillips, 8, and Isla Phillips, 6. The girls – who all served in the bridal party at Princess Eugenie‘s wedding to Jack Brooksbank in October, along with Princess Charlotte and Prince George – had fun chasing each other in the grass and petting dogs, then cooled off with some ice cream.

And doting big sister Mia made sure to check on 9-month-old sister Lena, who had her christening last weekend.

“They all seem very close,” an observer of the scene in the country tells PEOPLE. “The Phillips girls seem very taken with their new little cousin and I am sure they will with their new extra cousin when Meghan’s baby arrives.”

Mike Tindall pushed his younger daughter around in a stroller – but the observer says Mia also wanted to keep an eye on her.

“Mia just doesn’t stop – I don’t know how Zara and Mike cope with her,” the source says. “She is like a wound-up toy, from the moment she gets out of the car and they manage to put her back in.”

The observer adds, “She is quite strong-willed. At one point at the Gatcombe Horse Trials, she wanted to play with one of those rotating signs advertising a coffee stall and went to push it and climb through it. When Mike stopped her and pulled her away, she ran back to do it again.”

Both parents made sure to spend some quality time with Mia. Zara took a trip to the ice cream truck to get Mia a sweet dessert – mint chocolate chip! – and Mike had some fun spinning Mia around by her feet.

But Mia isn’t the only cousin who likes to goof off. Savannah memorably covered Prince George’s mouth on the Buckingham Palace balcony during Trooping the Colour last summer.

One day later, the cousins cheered on Prince William at his charity polo match in Gloucester, England. During the playdate, which included running around the field and playing with a Slinky, the daughter of William’s cousin Peter Phillips playfully pushed George down a hill when he attempted to sit next to her. Though George wasn’t injured and regained his balance, Savannah wasn’t unscathed as she was scolded by mom Autumn immediately after.

Savannah also had George and Charlotte giggling at Princess Eugenie’s wedding by mimicking the trumpet players.

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Princess Anne also made it out for the weekend gathering with her children, Zara and Peter, and grandchildren.

Princess Anne inherited a love of horses from her mother, the Queen, and became the first royal to compete in the Olympics when she rode in the equestrian three-day event at the 1976 Games in Montreal. Zara followed in her mother’s footsteps and won a silver medal at the 2012 Olympics as a member of the Great Britain Eventing Team.

Zara, 37, returned to competitive riding just two months after giving birth to Lena.

“The first time around my body was in so much shock,” she said in a promotional video for sponsor Land Rover. “It was like, ‘What the hell have you done to me?’ “

Zara shared that her return “feels good, actually,” and adds she now has her eye on a big target. “I’d love to try and get back on the team,” she says. “I’d love to go to another Olympics.”