MultiCompanyListAttribute.cs

public class DACExt : PXCacheExtension<DAC>
{
	#region UsrField
	[PXDBInt]
	[PXUIField(DisplayName = "My Field")]
	[MultiCompanyList(new Object[]
		{
			new Object[] { 2,  				//Company with ID 2
				new int[] { 1, 2, 3 },			//Values for Company 2
				new string[] { "1", "2", "3" } },	//Labels for Company 2
			new Object[] { 3,  				//Company with ID 3
				new int[] { 4, 5, 6 },  		//Values for Company 3
				new string[] { "4", "5", "6" }}		//Labels for Company 3
		})]
	public virtual int? UsrField { get; set; }
	public abstract class usrField : IBqlField { }
	#endregion
}

//Attribute that can change values depend on company
public class MultiCompanyListAttribute : PXEventSubscriberAttribute, IPXFieldSelectingSubscriber
{
	protected Object[] Conditions;

	public MultiCompanyListAttribute(Object[] conditions)
	{
		Conditions = conditions;
	}

	public virtual void FieldSelecting(PXCache cache, PXFieldSelectingEventArgs e)
	{
		foreach (Object condition in Conditions)
		{
			Object[] row = (Object[]) condition;
			Int32 company = (Int32)row[0];

			if (PX.Data.Update.PXInstanceHelper.CurrentCompany == company)
			{
				if(row[1] is String[])
				{
					e.ReturnState = PXStringState.CreateInstance(e.ReturnState, null, null,
						_FieldName, false, 0, null,
						(String[])row[1],
						(String[])row[2],
						null, null);
				}
				if (row[1] is Int32[])
				{
					e.ReturnState = PXIntState.CreateInstance(e.ReturnState, _FieldName, false,
 						0, null, null,
						(Int32[])row[1],
						(String[])row[2],
						null, null);
				}
			}
		}
	}
}