Collocations for incidental - adj.

be | become | consider sth, declare sth, deem sth
The fact that the concert made a profit was considered incidental.

completely, entirely, purely
Any resemblance of a character in this book to a living person is purely incidental.

merely
Information skills are not merely incidental to the curriculum but central to it.

almost | seemingly

to
It''s just a risk incidental to the job.