Integrate registration and login/logout between Caspio and WordPress authenticated users

I am part of a two-person team of individuals (not a company yet) so no bureaucracy to slow you down, and we have a small, very specific project involving user authentication, Caspio and WordPress. Can pay a portion up front if you can supply references, and will pay the balance promptly when the solution is in place and functioning. We are building a public-facing, membership-based WordPress web site which will use the BuddyPress plugin for WordPress to support social networking features, such as Groups. Normally those features can be accessed by the WordPress authentication system for user registration and login. However, the site also will incorporate some other features that will be supported by a Caspio database. The Caspio database features also require user registration and login. We do not want users to be burdened with and confused by two separate registration and login processes to use these different sets of features on the site, and we are not aware of any ready-made way to integrate a WordPress registration and login with Caspio. We have looked into OpenID and SAML but these are not viable options for this project. It is necessary to create some other type of integration to the WordPress database from Caspio. We have discussed this problem with our Caspio rep and we were advised to build the authentications for the site on Caspio, then develop the integration to WordPress. Given this situation, here is my project description: 1. Create a common registration and login/logout solution for both systems (Caspio and WordPress) that eliminates the need for members to register and login twice. 2. Create a method to share some user profile information collected at time of member registration with the "other" database. For example, if the Caspio authentication method is used, when a new user registers via the Caspio datapage for registration, some of the collected data should be inserted into a new matching record in the other (MySQL) database that WordPress/BuddyPress use. After user registration no more information sharing between databases is required. The information that needs to be shared is minimal -- user name, password, datestamp and possibly a bit more.