One browser instance for one suite_Maven+TestNG - selenium

Question

I have sets <test../test> with classes that run in parallel. Now a browser instance is opened for each class. How to open one browser instance per set (eg. for test name="admin") instead of per class?
StudioTests.xml:
suite name="Studio Tests" verbose="1" parallel="tests" thread-count="4"
<parameter name="browser" value="chrome"/>
<test name="admin">
<classes>
<class name="tests.project.Action"/>
<class name="tests.ProjectTransform"/>
</classes>
</test>
<test name="superuser">
<classes>
<class name="tests.Auth"/>
<class name="tests.project.Action"/>
</classes>
</test>
public class BaseTest:
#BeforeClass (alwaysRun = true)
public void setUpMain() {
if (System.getProperty("os.name").toLowerCase().contains("win")) {
driverPath = "src/test/resources/chromedriver102.exe";
}
else {
driverPath = "src/test/resources/chromedriverlinux102";
}
System.setProperty("webdriver.chrome.driver", driverPath);
LoggingPreferences logs = new LoggingPreferences();
logs.enable(LogType.BROWSER, Level.SEVERE);
ChromeOptions options = new ChromeOptions();
HashMap<String, Object> chromePref = new HashMap<>();
chromePref.put("profile.default_content_settings.popups", 0);
chromePref.put("download.default_directory", System.getProperty("user.dir"));
options.setExperimentalOption("prefs", chromePref);
options.addArguments("headless");
options.addArguments("window-size=1800,1000");
options.setCapability(CapabilityType.LOGGING_PREFS, logs);
options.setCapability(CapabilityType.UNEXPECTED_ALERT_BEHAVIOUR, UnexpectedAlertBehaviour.IGNORE);
driver = new ChromeDriver(options);
driver.manage().window().maximize();
driver.manage().timeouts().implicitlyWait(10L, SECONDS);
driver.get(System.getProperty("studio_url"));
}
#BeforeClass (alwaysRun = true)
public void setWaiter () {
driver.manage().timeouts().implicitlyWait(10L, SECONDS);
}
#AfterClass(alwaysRun = true)
public void closeBrowser(){
driver.quit();
}