Today I import my contacts from an MS Access database via manual export to csv>csv>vcard transformation. I want a closer integration, preferably 2-ways, ie when changes are made in the Access database I want them to occur also in the contacts fields, and vice-versa.
I welcome any ideas on how this can be done?
I would think you would need a piece of software that understands the format of your Access DB and CalDAV. Then it could properly synchronize the data between the two storage formats. You may have to write that software, or pay to have it written. If both systems allow changes, you have to have code, and likely human intervention, to resolve the conflicts which will inevitably happen.
The CalDAV part is likely available in a library you can use while writing the rest of the app. The Access part will likely be harder if your schema is not a well known variety. The merge logic will probably be the most “interesting”.
Hello, unfortunately such feature is out of scope for our project. 
Thus I will close this issue.
Have a great day