How to populate a drop-down list code or key column from table a and description from table b

Looking for code example to populate a drop-down list comb-box where the key1 column is from one table and the description column from another. For example:

Table A is the CustBillTo where you would define alternate BillTo customers for the a customer, seen uploaded snapshot:

I have to lookup the customer name and use it for the description column in the drop-down list. As you can see from the snapshot, table A only has the Customer ID and BillTo ID.

The code example I have for populating a drop-down is the following, I would have to call the adapter for the CustBillTo table. However, the table does not have the customer name only the customer and bill to IDs. The customer name is contained in the Customer table. Can this be done? Can the search adapter be changed to call a BAQ or some other way?

	bool recSelected;
	string whereClause = string.Empty;
	System.Data.DataSet dsUD01Adapter = Ice.UI.FormFunctions.SearchFunctions.listLookup(this.oTrans, "UD01Adapter", out recSelected, false, whereClause);
	if (recSelected)
	{
		// Set EpiUltraCombo Properties
		this.rsiCommentCode.ValueMember = "Key1";
		this.rsiCommentCode.DataSource = dsUD01Adapter;
		this.rsiCommentCode.DisplayMember = "Character01";
		// MGA - Was this.rsiCommentCode.DisplayMember = "Key1";
		string[] fields = new string[] {
				"Key1"};
		this.rsiCommentCode.SetColumnFilter(fields);
	}
}

I used a different approach. Instead I called the Erp.BO.CustBillTo for the column properties to pull the necessary columns. I discovered this after performing a trace.