Do children-in-law count?
My husband's parents are hoarders/compulsive shoppers. Their house, while usually "neat", is stuffed to the gills with the things they collect.
Her: anything antique. The walls are covered with rug beaters. Every window sill is lined with old bottles. One spare bedroom has near 100 old photos of people unrelated to the family on the walls. Furniture of all sorts. It's difficult to walk in some rooms to get between all the furniture. Antique kitchen gadgetry hangs from the ceiling in the kitchen. Doilies stacked in the closet. It's all tidy, in a sense, but there's just. so. much.
Him: knives...thousands of pocketknives are in gallon ziplock bags in the rec room in the basement. Knives in cases on display. He keeps buying more knives by the lot on Ebay. Like lots of 100 or more.
Flashlights in every conceivable nook and cranny, in every type and size. DH and I used his truck once to pick up a couch. In the console, I counted 36 packet of ketchup from fast food drive thrus, and there were innumerable paper napkins stashed throughout the truck along with salt packets. Hundreds of salt packets. His garage is not used for vehicles, rather it is a warren of workbenches piled at least 2-3 feet high with bits and pieces of mechanical/electrical/woodworking stuff.
They have an enormous chest freezer stuffed with food. It's just the two of them, but there is literally more food there than they could eat in a year, it seems. When the big "Y2K" scare was on, they went in with a group from their church on mass quantities of staples such as rice, powdered milk, oats and flour. They stored it in the closet under their stairs in 5 gallon plastic pails. They are still there, at least 25-30 pails. They offered some to us last year. Needless to say, it wasn't any good. We chucked it, but the ones they kept are still there. They buy large quantities of dollar store toys and junk for each grandchild for birthdays and Christmas. We've been fairly outspoken in our wish to avoid consumerism in our home, and a focus on natural materials. I'd much rather DS receive high quality wool long undies and a wooden truck than 3 boxes of 25 plastic toys, or Elmo this or that, or whatever. It's created monsters at gift-opening times...like, rip! rip! toss! what's next? that's all? pout. We sooo don't want that for our kid.
DH has inherited some of their tendencies, but I am much more minimalist and continually purge and donate. He doesn't notice when I get rid of most of his things that I've purged. I usually set a date and say "if you haven't addressed this pile by Friday, I am going to take care of it, okay?" and follow through.
DHs parents are helping us a lot with items for our new home right now...so I feel bad venting about them. But, on the other hand, they are trying to put some hoard in here too, so I have to constantly keep it in check. It's hard, because we do have a lot of room and storage space in our large home, but that doesn't mean we want to fill it up with stuff. We have a lot to purge on our own! We don't have much leeway with our budget, and no extra to spend right now. We've made that abundantly clear to them, but they wave it off, saying that it makes them happy to help us and give us things.
My mother in law checks Craigslist compulsively, and emails me at least once daily to tell me about this "great buy" she found on x, y or z thing that she thinks I might need. She has found some great deals on things we did really need, like laundry machines and a lawn mower, so it's not all bad.
On their last visit, they brought (in addition to the things we needed, like a washer, canning jars and a large wool rug) 48 cans of tuna, 10 lbs of dried cherries, 2 gallons of hand soap (which I wouldn't accept because it was all chemically), 48 rolls of toilet paper and 6 large bags of clothes for DS, ranging from 2T to 4T that MIL had found at garage sales and resale shops. Yikes!
Sorry this is so long, don't mean to hijack. Just adding a big "amen!" to decluttering and fighting the hoard. I'm going to be spending more time in this area of MDC for sure.