Can someone point me in the direction of a good tutorial or instructions on how to build Parent-Child relationships in FM?

I have a number of general business types (Retail, Restaurant) that I want to subdivide into more specific groups (Retail:Mens Clothing, Retail:Womens Clothing), but I still want to be able to search and sort on the Parent cat... and I would like expansion flexibility to further narrow the Child cats (Retail:Mens Clothing:Shirts, Retail:Mens Clothing:Slacks). (I know how to do this in MySQL, but FM stumps me).

Well you would develop this in Filemaker exactly as you would in any other relational database system. Specifically you do not need relationships as what you are describing is really just a more refined system of describing the record.

In this case you could make your Types and SubTypes seperate files, but I do not see that they are actually distinct types of records and are really just a way of describing another record. I would just stick them into a couple of fields (i.e. Type, SubType), so that you can find and sort by them seperately.

Of course, you may have other unstated problems or requirements that are leading you down this path. Is this the case? If so what are the requirements?

Hmmm. Might work. Would ultimately need to create a dropdown menu from a Value List generated from merged Type Subtype fields. Will have to work that through.