Yes, that is not a problem.

Where I did have an issue was a few years ago on an A380 JFK-CDG, with 9 seats in P. At take-off, 3 seats were taken. Me, and a couple that I had already met with their 3 teenager/young adult kids in the P lounge in JFK. When meal service started, each one of the kids came forward to the P cabin and took one of the free seats, and got the full P meal service. When I woke up the next morning, those kids were still asleep in their P seat or walked around the cabin in their P pyjama.

I didn‘t exactly complain, because my own experience wasn‘t impacted at all. However, when the CDC came round at the end of the flight to ask how the flight was, I did ask him what I‘d have to do next time to transport my entire family in P as well without buying them P tickets. He looked embarassed but didn‘t really apologise and give an explanation.

Call me narrow-minded or whatever, but what bothered me was the sense of entitlement that family apparently had to just use the P cabin as “theirs”, and the airline going along with it.