Search form field - need to duplicate and transform from dropdown to checkbox type

Hello,


I dont know if I am the only one, who has the problem. I got some essential listing fields which I want to add to the search forms. But those ones are dropdown fields and I know that visitors would search for more than one of those items in the drop down fields.
So would be there a way to copy or transform the dropdown field to checkboxes? Its the same with the categories. Some buyers would like to search in more than one category with one search request.

It would be nice, if we could choose search field item forms (radio/checkbox/dropdown)

Thanks in advance!