How to bind the results of one combobox to another combobox in Visual Studio (C#/SQL)

I am creating an interface to display car owners and their respective cars (think, a pretend DMV).

I have a combobox bound to the database that autopopulates a few text fields (first name, last name,etc), and a second combobox that populates vehicles (make, model, etc) but I am struggling to get the second combobox to display only the cars affiliated with the ownerid in the first. They are connected via primary and foreign key (see images)

Database:

Interface:

I have tried several intuitive setups for the data bindings in Visual Studio, but all of them display all cars in the database, not just the ones with the correct ownerID

EDIT: Here is the working solution that i used thanks to Morr1gan, below. I just placed these three lines into the first combobox's SelectedIndexChanged event handler.

int selectedOwnerID;
int.TryParse(ownerComboBox.Text, out selectedOwnerID);
vehicleBindingSource.Filter = $"CarOwnerID = {selectedOwnerID}";

So, to bind the results of one combo box to another in VS, you can use the SelectedIndexChanged event of the first combo box in order to filter the data that is shown in the 2nd box reliant on the item in the first.

For the purpose of your question, I will be using naming conventions of my own. Feel free to replace appropriately and let me know if you receive any syntax errors, please. You can create a data source for your second data combo box that includes all of the car info, such as the owner ID in your case-scenario. Then set a DisplayMember property of the second of your combo boxes (if you have MSAccess, you can do this fairly quickly and easily), property of the second combo box to the car make/model or whichever you desire.

Once you do that, you could also set a ValueMember property of the second combo box to the car ID or as long as it is a separate unique identifier.

Using the SelectedIndexChanged event of the first box, write your code so that it filters the data in the second combo box based on the selected item in your first combo box. You can do this in MSAccess via setting the DataSource property of the 2nd combo box to a filtered data view or data table that only will include the cars with the appropriately selected owner ID.

Example (Raw):

// Assuming 2 boxes named ownerComboBox and carComboBox 

// Setup the data source for the 2nd

carComboBox.DisplayMember = "MakeModelYear";
carComboBox.ValueMember = "CarID";
carComboBox.Datasource = carTable

// Setup the event handler

private void ownerCombobox_SelectedIndexChanged(object, sender EventArgs, e)
{
     int selectOwnerID = (int)ownerComboBox.SelectedValue;

// Filtering out the data in in the carComboBox based on selected owner's ID

DataView carView = new DataView(carTable);
carView.RowFilter = $"OwnerID = {selectedOwnerID}";
carComboBox.DataSource = carView;

In the above example, carTable is a Data Table that will contain all of the car data as well as owner ID. The MakeModelYear field will concatenate the string of the car's make, model, and year, then use it as the display value for the second combo box.

The ownerComboBox_SelectedIndexChanged is an event handler that filters the data from carTable based on owner's ID then sets the DataSource property of the other combo box (2nd), to a DataView that will only include those filtered cars. Will also update the 2nd box as well based on your selected item in the first combo box.