Nip it in the bud NOW. As someone else said, it's an INFLUENCE bribe. My career powerbattling my parents over my kid started when my mother REFUSED to honor my demand that she NOT PUT SALT on a baby's food like she did her own.
It was an OMEN. I should have stopped having him stay there for babysitting IMMEDIATELY. But I thought it was a nice thing when I had to go back to work part time when he was age 14 months and later full time when he was 3 years old. (company reasons). I thought it was more important to have that bond than "a few fights over values". FAIL. WRONG.
Let them shut down. This shows you THEY HAVE A PROBLEM.
Stop sending them over there.
ALL gifts must stay THERE.
Be crystal CLEAR and EXPLICIT with your parents without anger. AND YOUR CHILDREN.
If they break the rules the STUFF disappears. I don't really care WHERE you get rid of it. REDIRECT them from STUFF to activities like sports or whatever they like and do not allow the parents to buy the 2000.00 of hockey equipment. Buy it USED at a second hand store or whatever.
I promise you it just gets worse.
One year behind closed doors, I heard my parents scheming to put my 9 year old in a PROFESSIONAL kid go cart complete with the fire proof outfit etc. For races on a quarter mile oval banked racetrack and OTHERS that actual RACE CARS raced on.
My step father had a 48 foot boat when I was a kid for weekends etc....and sold it for a modified stock car hobby
...that competed all over the east coast. So he was INTO that crap. I hated having to go there instead of our nice boat life.
Anyway, we had a fight about this go cart scheme and I KNEW I got nowhere with it. They delivered the entire package including the custom airbrush helmet, custom painted truck and PIT CREW with matching OUTFITS FFS.
I had NO IDEA the "season" lasted every single weekend both days from early spring till late fall.
This is just ONE EXAMPLE of the selfishness, overreach and disrespect they showed me. NO REGARD for what was best for the kid and learning how to live without being showered with stuff every day of his life. NO concern whatsoever that it was a SLIGHT ISSUE that I and his father would not SEE HIM every weekend for most of the year unless we dragged ourselves to that disgusting place with them.
They kept upping the ante and doing everything humanly possible to entice him to want to stay at their luxurious home including putting a $30,000 pool in. He NEVER had a single chore to do. Their idea of chores was sitting on my father's lap while he drove the lawn tractor around. Why? Because they could and were bored and he was their RE-Doo.
PUT A STOP TO IT NOW for the sake of your kids.
My mother left a substantial estate/trust to my son, which was much appreciated. Spread out until age 40. BUT it did NOT make up for all the lessons he failed to learn growing up that way and the ongoing lack of responsibility he grew up with and even NOW at his adult age says WTF. Also, as she and he got older like a teen, she was unable to see what he was really doing when going there for the weekend. Like during poker parties in the basement sneaking beer in and her being CLUELESS because she was going to bed earlier etc etc.
It's a SPIRAL. They get more friends over in that neighborhood than yours and so it begins. The nagging the phone calls etc.
There are PLENTY of ways for well to do grandparents to throw money at kids like a expensive family cruise once a year to an exotic or exciting place. That won't create a series of problems for your kids.
But NO. Because that prevents them from reliving their parenting all over again in their senior years.
Lucky for me I don't have that "disease". My kid has no kids and I am THRILLED.