AX2009: Field lookup to multiple tables

Hi all! I need to do a lookup field to multiple tables, because in this field you can find values from two different tables.

I have tried to do this without extended data type, but when I add this field to an AXGroup in Visual studio, in Enterprise Portal doesn’t appear the button lookup of this field, I only have the text box.

Is there a way that I can have an extended data type related with two tables??

If It isn’t possible, do you know another option?

Thanks in advance and greetings.