Rule Controllers are independent of each other. If there are multiple Rule Controllers defined for a masking set, each Rule Controller can be configured to connect to the same Sql Server and database or entirely different ones.
The Data Masker software is multi-threaded and can run up to eight rules in parallel. It is common to have a situation in which certain rules cannot run simultaneously and must run sequentially one after the other as a chain. The execution order of the masking rules is controlled through the use of rules blocks and dependencies. Please see the Rule Blocks and Dependencies help page and view the Using Rule Blocks and Dependencies tutorial [local] [internet] to understand how to explicitly control the execution order of the masking rules. Note that Rule Controllers themselves can have a designated rule block. A Rule Controller (and hence its dependent masking rules) with a lower rule block will always execute before a Rule Controller with a higher rule block.
A Rule Controller is automatically created when a new masking set is built using the New Masking Set wizard. Additional Rule Controllers can be created by launching the New Rule Controller form using the New Rule button located on the bottom of the Rules in Set tab.
How to create an additional Rule Controller