Multiple titles in one form

Hi:
I have a form with an html inserted text (default title), and 3 custom fields as titles too, which changing according a selected menu.
So I need your help to create a filter (I’m sorry my “Tarzan like” php code) like this:

add_filter(‘cf7_2_post_filter-post-title’,’filter_post_title’,10,3);
default $title = echo “My default static title text”;
else
$title= “[post_custom_field-title_one]”;
return $title;
else
$title= “[post_custom_field-title_two]”;
return $title;
else
$title= “[post_custom_field-title_three]”;
return $title;

Thank you.