It would seem the best practice for skill nodes is to maximize them to include your 2 best or most used skills. As a Merc i would want a tri core with Ishtar and AFA as often as possible, however i have been advancing the levels of the cores i do use.
On to my question, i have been able to craft better cores and then remove a lvl 3 core, and use the new lvl 1 core with the desired skills. Then enhanced with the lvl 3 core bringing it to lvl 3.
I am just worried, that this is maybe a glitch, and not a thing.
Can anyone confirm this is a fact and nothing to worry about. Sure helps get perfect cores.