The only safe way to allow two concurrent agents to modify a single database is to have both of them communicate with the database via a gadfly server that arbitrates database accesses. Of course, two programs can have read-only access to the same database in separate memory instances without any problems. My email suggests that quite a few people have been using Gadfly, including professional and industrial organizations of various sorts. Gadfly has been included in a number of CD-rom publications, such as Linux distributions. Yes, please contact Chordate for paid support.
Unpaid support is more popular, but less reliable.
At this point the current plan is to maintain the current implementation and fix any bugs that arise. Gadfly will support backwards compatibility of existing databases. There is no formal mechanism. One possible approach would be to join the Python Software Association and then get a starship account and then put your contributed code there. Chordate may add links to contributed code to the Gadfly documentation at their discretion.