Running two instances of same JRE version with different parameters

I want to increase the initial RAM allocated to run a particular jar that needs it. However, passing the parameter “-xms1g” to the system JRE seems to prevent the launch of a JNLP file that I need to submit credentials for access to the U.S. Patent Office Private PAIR website:

https://ppair.uspto.gov/TruePassWebStart/AuthenticationChooser.html > “Authenticate with Java Web Start (new method)”.

When the JNLP launches properly, it opens a GUI that prompts you to entire the filename and path of a certificate in one field, and a password in another field, and then it automatically closes and brings up the private PAIR website in your web browser, if your credentials are valid. You don’t have to have a certificate or password to duplicate or test for my issue, as my problem is not getting the prompt to pop up.

For consistent testing and development of my jar, I want to run it on the latest JRE release, which I have to assume other users of my jar will be running. I believe I may also need to use the latest JRE release when launching the JNLP to access the USPTO, for security reasons. Maybe someone who understands cyber-security better than I do could tell me that JRE version doesn’t matter when I am launching a JNLP file instead of running an applet through the Java browser plugin (the so-called “old method”), the latter plugin being what Google Chrome stopped supporting, but I don’t want to assume that.

So ideally I would like to have two installed instances of the same (latest) JRE version and pass the -xms1g parameter only to the instance I use to run my jar, not to the (system) instance that launches the JNLP. Is this possible? When I tried executing the JRE installer twice, selecting different folders, I found that the second installation had deleted everything from the first folder.