Hello joetravel,
Your category and role fields should both be a text fields. The category field will hold the text values Member, Officer etc. You should establish a relationship from it to a corresponding field in a table where the related Role values are stored (one on each record, against the corresponding category).
Then, if you set up the value list for the Role field to take values from the role field in the related table, but instead of choosing the option for 'All values' from that field, instead choose the option for 'only related values'. When you do, the list for the Role field will be filtered according to what has previously been selected in the Category field.
