Child's temper/attitude changes when with wider family

[languising]

I have a 3 year old. He's a lovely polite sweet boy, however I've noticed that when we're with my parents or the in-laws he can have a little more attitude with me and his dad.

I'm assuming this is pretty normal? Just a bit excited and impatient with interruptions to the toys and attention from lovely grandparents?

My experience is that grandparents are pushovers, so the kids get cocky. Try to nip it in the bud.

My parents are horrendous with our eldest, always giving her money and/or stuff so she likes them much more than me. Being a 15 year old, tbh she can be a total ass to me and I have to remind her who does everything that matters for her. They used to look after her when I worked so are a lot closer to her than our other 4 where I've been a sahm. Really grates on me.