Insert into a specific partition, create if not exists

So I have my master table:

p_reports: id(pk), web_id, other(data)

At the moment I create my partitions which inherits from p_reports by using:

CREATE TABLE IF NOT EXISTS reports_#{web_id}(CHECK(web_id = #{web_id})) INHERITS (p_reports);

Then I do a bulk insert into that table, this works fine, but for this I need to group to create blocks of data for the specific partition, and do multiple inserts.

Is it posible to have a function, so I can send all my data at once, and the function will create partitions if they don't exist and then insert the data in the corresponding partition?