Multi select listbox control pre-checked in Infopath form

I Have a InfoPath form, and Multi select checkbox & dropdown in it. When I select item in dropdown, it will filter and show the Characteristics of the item in Multi-select list box. I done it using filter.

But the item has some of Default Characteristics, it need to be checked automatically when I select item.  Ex: if I select "Dog" in the dropdown, The multi-select list box will shows as  Animal, bite, bark.      Animal & Bark   are default items, it need to be pre-checked automatically when I select Dog in the dropdown. need to do this with InfoPath form code behind,

Any help, links and ideas will be appreciated. Please help me .....