To Ankylus' point, If you hold it up and water runs out, it has no insulating value. Water conducts heat well no matter what fabric is trapping it.
Wool will actually generate heat by exothermic reaction up to about 30% of its weight in water, After that, it's just wet and takes forever to dry in the field.
Polyester fleece, batting and pile is hydrophobic. The strands of fabric will not absorb any water (recycled pop bottle "plastic") so it drys rapidly.
I suggest a total change of clothing sealed in heavy plastic bags along with the sleeping bags. If they can get in a dry sleeping bag under a tent, nothing too awful will happen. Some spare sleeping bags would be prudent. Extra dry socks in zip-loks over and above all else.
Be sure the tents don't leak. A plastic sheet inside helps back up the floor coating. A "blue tarp" outside is insurance against any doubt about the fly.
Some think any jacket with a nylon outer layer is waterproof. Strange, but I have run into that error many times. They need actual rain gear. Ponchos are least expensive, but the cheap plastic ones tend to magically develop holes.
Footwear that keeps out water is a must. If waterproof boots are not available, the "sock sandwich" will do for a weekend: plastic bag over foot/then socks/then plastic bag. Foot gets damp from perspiration, but socks stay dry to insulate. Needs to be changed out a couple of times so extra plastic bags and socks required. Cold wet feet can result in "immersion foot" (AKA "trench foot"), qv.
If you suggest "foam pads," some may show up with open-cell foam, AKA "sponges." You need to specify closed-cell foam pads for those that will not bring self-inflating foam-filled air mattresses (e.g. Therm-a-rest). Re-purposed closed-cell carpet padding will do the trick. I have been scrounging it for years, avoiding the leavings "marked" by cats.
Hopefully, your site has a "picnic shelter" or you have a dinning fly large enough to gather for cook/eat/socialize if it's pouring. The hot cup of something Ankylus mentions is all the better out of the rain.
Hot water bottles - the kind that does not leak - produces sleeping luxury in the midst of cold.
Towels to dry off feet before replacing foot layers.