You can have only 1 Prod and 1 Staging environment... all other environments coded into your Launch Property will be tied to the same suite...
That is unless you have some fancy code overwriting the suite account on your extension, which I doubt.
This will mean you need to understand where your NGT environment is pointing, and you will have to create a segment to only pull data from it...
Let's go with a simplistic example... Let's assume you have 3 testing environments:
test1.domain.com
test2.domain.com
test3.domain.com
(all three of these will be putting data into testsuite)
And your NGT environment is pointed at test3.domain.com.
When you open up a Workspace area on testsuite, you will need to create a segment looking for traffic on "test3.domain.com" (eVarX "URL" contains "test3.domain.com") - that is, assuming you are tracking the URL into a eVar... if you are not... then there may be another very specific combination of dimensions that you can use to isolate the data... without knowing your tracking setup, I can only offer general advice.
If you have nothing like a URL or something to segment on... perhaps you are tracking the ECID into a dimension... you could segment traffic specific to yourself (not the same thing, but if you are testing the NGT environment, you could potentially isolate the data to your own testing....)
