The CP Google Maps allows create routes between points defined in a same post or page, but sometimes is needed create routes to connect points belonging to multiple posts.
For example, suppose you are creating a blog about your vacations in Europe, and you’ve created a post for each country or place of interest. Your blog will include a map in the homepage to display all points, and the routes of the journey. Your blog should connecting points in different posts or pages.
If you have installed the “CP Google Maps” plugin, version Pro equal or bigger than the 5.0.1, you simply should define as the final point in the Post A , the first point in the Post B. For example, if your vacation began in Spain, and the Post A include the points visited in Spain (Andalucia, Valencia, Barcelona), and the Post B is about France, the first point in the France post should coincide with the last point in the Spain post, in this example, Barcelona was the last point in the Spain post, so you should create a point that represent Barcelona, as the first point in the France post.
http://wordpress.dwbooster.com/content-tools/codepeople-post-map