OK, First and foremost, unless it's in writing in the contract, what the listing agent said means NOTHING legally. Also, do not presume that an agent holding the house open for a sunday open house is the listing agent. It may be someone else holding it open.
Second, the contract is between the buyer and the seller, the agent has nothing to do with the legal contract in terms of legally giving you the right to anything, so even if the agent says it, it means nothing, only if the seller says it IN WRITING does it have any meaning.
Third, when the listing agent said that "everything" was staying, she was probably referring to things like the refrigerator, the curtains, etc. which are the things that people typically ask to stay (in Missouri, if it's attached it stays, if it isn't it goes - curtain rods and blinds stay because they are attached, fabric curtains do not, because they aren't attached, a built in microwave is attached, a microwave sitting on a shelf or on the counter does not stay, etc). Homes don't typically come with any personal property (furniture, etc) since then you are mixing the sale of personal property and real property (the home and land) and that will throw your mortgage lender and the appraiser a real problem (in fact even when things like the refrigerator and washer and dryer stay, we have to put in the contract that they have zero worth, since otherwise when they do the appraisal they legally have to include those items in the value and the bank won't loan you the money for those items, only for the home and land. Also anything left that is personal property will be "as is" with no warranties or guarantees on condition.
Fourth, if this is an estate, then the sellers are typically several heirs and the one who is communicating with the listing agent, may not be the one who is responsible for dispersing the items in the home and settling the rest of the estate as far as the personal property is concerned. The listing agent may not even really know what has already been given away to other family members/sold/given to charity, etc.
Now, Do you have a contract on the home? If you do, then all of this needs to be specified in the contract. If you do not, then what is staying, not staying is as of the point of the contract, not a previous list. Once you have a contract, as is specified in the contract EVERYTHING needs to be in writing. Your agent is legally there to protect your interests and should insist on a complete list of what stays and what you want removed that is a legal part of the contract, not just a piece of paper even if everyone signed it. An agent who doesn't do that, isn't protecting your interests.
If you are working with just the listing agent, rather than with your own buyers agent, then you are probably screwed because the listing agent has a responsibility to protect the interests of her own client (the seller) and does not have a responsibiltiy to protect your interests.
If you have a dual agency contract with the listing agent (saying that both the buyer and the seller give the listing agent permission to work with both of them), then the listing agent has a responsibility to protect both sides interests, but quite frankly, it is very difficult not to "favor" the seller when that happens since the contract with them typically came before the contract with the buyer.
Now, once you have a contract on the home, then you don't have the right to keep going back to the home, except for the building inspection and the final walk through (as is stated in the St Louis contract), so typically you wouldn't know if things are now gone unless you are going back through open houses (the sellers typically keep the home on the market looking for backup contracts as long as possible) or are doing the inspections.
Go through your contract and make sure what is stated as being left. If it's not written into the contract the seller has every legal right to remove it prior to closing. Ask your agent to sit down with you and step by step go through the contract with you explaining your legal rights.
As long as you have a contract with another agent, I can't legally sit down with you to explain the contract and go over things with you (and please note that in St Louis, if an agent other than the listing agent or an agent holding the house open for a sunday open house, has shown you the home, even if you didn't have a buyers agency contract with them, they are still the procurring cause and legally should be paid at least part of the commission for the sale of the home if you buy it. Once you are in contract negotiations on a home (even if you don't get an accepted contract and come back a month later and resubmit a contract with a second agent on the home, the first agent is still due a commission), if you're not in a contract situation, call or email me and I'll be happy to go over it with you and help you determine what is truly going