In my WordPress project admin, I created post object of custom post 'People' in custom post 'Project'.
Now when adding project if required people isn't available user should be able to add people. For this I am thinking of adding 'Add People' link which on click will show the custom fields of post 'People' in popup. On saving data, it will be selected in post object.
Is this possible? If yes how am I approach this?
I googled but not getting any idea about how to approach this?
What will be the best solution for this case? Any suggestions are welcome.
Sounds like you've got a custom post type of "Project" and then you're trying to find a good way of adding people to that project.
I'm not sure if you have a custom post type of "Person" but it sounds like you might, if that's the case then the easiest approach would be to have whoever is entering data to just go and add the new person from the custom post type of person. Then have a relationship field in project linked to person.
If Person isn't a custom post type and it's just a field (so all that you need to know is the person's name) then it might be simpler to use a custom taxonomy where a new term can be added directly from the meta box. see this doc page for more info on that.