So, it seems you want the filter from another column (description) while you set DataTextfield="cost_area" and DataValueField="subproyect", correct? I think set AdditionalSearchFields="Description" can achieve the scenario.

e.g

On my attached sample, I have 2 WebCombo. One is bound to Customers, the others is Orders.

I set AdditionalSearchFields into "City" while DataTextFiled is ContactName and DataValueField is CustomerID. With this way, if i type London, i can filter the data. With this functionality, I also linked with WebCombo2.

Hope this helps.

Regards,
Handy 

Hi good day, AdditionalSearchFields="campo3" this is the property that solved my problem.

But a have other question, do can define other column diferent of UseDataTextField or UseDataValueField for link the webcombos
i'm using FilterDataMember but not works.

Hi,

I am sorry but i don't quite understand your point, could you explain more detail about the requirement? 

Regards,
Handy