::All you say I understand, this is just a quick reply. I will go through the links. A "background in software is enough" is a little patronising. But I am not here to give you my CV, just to help. I worked for a company for about eight years doing object oriented databases, not pretend ones flattening it to SQL or whatever, so am  well on the ins and outs of relational theory, if you care for that kind of thing. It sounds like a job for a reduced table set, but I will check out what you are trying to achieve. We won't just get it right, we'll get it written.

I can't say too much about what I do professionally.

Best wishes S.