Multiple JREs and java.security

[Pho Tek]

Everytime I needed to add a new security provider into the
java.security file; I always need to go through the rigmarole of looking for all occurences of java.security in the filesystem
and editing them to see if takes effect. This problem stems
from the fact that I usually have multiple JREs installed from JDKs and also other applications that bundle it. Note that even with my JAVA_HOME variable set to the correct place; the real java.security is usually somewhere else.
Does anyone know a good article on how multiple JRE coexists and how to make one the default or something ?
Thanks
Pho