Display Muliline text box in request property

Hello All,

I'm  using request property and leverage of the AdditionalData column in Personwantsorg table. I want to display this field as a muliline textbox. currently it' displayed as a simple textbox.  I've found a muliselect check box in the database schema correstpned to this column but when check it doesn't change it to a mulitselect text box. 

Thanks In advance

Tony