Combination of three pages into one

I have three web pages that need to be combined to display a navigation route on MapBox.

1) First page has the user adding their start and end co-ordinates which are written to a database using php. The database is created and the page is written.
2) Second page is curl which makes a call to a third party service provider to request the route. This must be included into the page and only executed on submission of new route co-ordinates from the existing page 1. The results of the api call need to be written to the db, Update needs to be done to the database to indicate that waypoints have been received so that the co-ordinates are not rerun on the next request.
3) Third page is the call of the waypoints from the database and displaying on the map.