Ideally, when a parent passes away, they leave a will behind. It notes how the personal items they are passing to their heirs should be split up. It may say specifically how this should be done — Child A gets a certain painting, Child B gets the book collection, etc — or just provide general guidelines.
Either way, nothing should be done outside the scope of this will. The estate executor is responsible for inventorying the deceased’s personal items and working on the distribution. The heirs may have some level of involvement, but it is the executor who mainly does this job.
However, there are cases where heirs will go to the parents’ home and take personal items. They may have something in mind that they’ve always wanted to inherit, perhaps so that they can one day give it to their own children. They have keys to the house, so they figure they’ll grab what they want before anyone else does.
What options do you have?
If you’re an heir or a beneficiary and someone does this, you may feel like they’re treating you very unfairly. This wasn’t meant to be a free-for-all, with everyone just running to the house to take what they can. It may also violate your rights if items that you were allotted in the will are not in the inventory because someone took them in advance.
Should this happen, you may want to look into all of your legal options. You do not just have to accept that this has happened, especially if the will specifically left those items to you. Litigation (or the threat of litigation) may be the only way for you to get fair treatment.