I wanted to come back to your suggestion about the use of an external file, to let you know that it proved necessary, especially when sending updates of the software. Thanks for the suggestion.The 'side-end' configuration db is supplied with the app on purchase & is initially blank. On initial setup the connection details to the backend are entered & stored in the side-end db for future use.
On the rare occasions that these settings need to be changed, these can be updated by the program administrator.