Protecting databasesYou can restrict what users can see and do in a database file by definingand . For example, you can:•Password-protect a file•Allow data entry only•Allow browsing but prohibit database changes•Restrict access to specific tables, records,, and layouts•Give certain users full access to a file, which allows them to define tables, fields, relationships, data sources, and access privileges for other usersYou can also control access to a file’s(including its tables, layouts, scripts, and value lists).Although your operating system includes file security features, you should use FileMaker Pro access privileges as the fundamental way to control access to and protect the security of your database files.It’s especially important to protect FileMaker Pro files that are shared with other FileMaker Pro users via the, with web users via , and with / clients. These shared files are more vulnerable because they may be more widely available over your network.
See "Editing record access privileges" in FileMaker Help and check out this particular sub section: "Entering a formula for limiting access on a record-by-record basis".
You may need to set up a "user table" where you have one record for each user's account name with a list of the brands for which they are permitted access.