Here is a quick query to see the internal "point in time" memory clerk use for the sql instance

SELECT @@servername AS InstanceName,SUM(single_pages_kb)/1024 AS [SPA Mem, Mb]

FROM sys.dm_os_memory_clerks

ORDER BY [SPA Mem, Mb] DESC

You would need to run this against each instance and run it multiple times to see how things are changing or not changing.