You cannot merely tell your family what should be done with your assets after you pass away. You need to go through the process of getting a formal estate plan drawn up.
While we all would hope that we can rely on our families in this way, there are legal and practical reasons why it is unwise to do so and why people need to get a proper estate plan. This was discussed in a recent Fontana Herald News article titled "Having estate planning documents is very important."
The biggest issue faced by your family if you do not make an estate plan, is that your family will not decide who gets your property. Instead, the courts get to make that decision and they do so by following statutes that determine who gets everything.
The person who the courts decide gets everything, might not choose to follow any directions you have given to distribute that property to other people. In some cases, it might be impossible for them to follow your wishes, even if they wanted to, since they could face negative tax consequences.
If you can take the time to tell your family how you want your property divided up, then you can take the time to get a formal estate plan that will actually carry out your wishes.
Reference: Fontana Herald News (August 7, 2017) "Having estate planning documents is very important."