Hi @mcboschman, no I am afraid you cannot use both the Core SDK and Pro SDK at the same time unfortunately as they have very different libraries.
However, I will check with Tobii Pro SDK support if they know of any free fixation filter algorithms already developed with that SDK that you could use ,unless you have already asked?
In any event, the methodology we use is open to the public and can read a bit more @ https://www.tobiipro.com/siteassets/tobii-pro/learn-and-support/analyze/how-do-we-classify-eye-movements/tobii-pro-i-vt-fixation-filter.pdf/?v=2012