in·ci·den·tal·ly 
/ˌɪnsəˈdɛntl̟i/ adverb
/ˌɪnsəˈdɛntl̟i/ adverb 1 : as something that is less interesting or important
▪ The report discusses the problem only incidentally. [=in passing] ▪ Not incidentally, the market slump was followed by widespread layoffs. 2 — used to introduce a statement that provides added information or that mentions another subject ▪ I recently met his wife who, incidentally [=by the way], is a well-known author. ▪ This product is the best—and, incidentally [=by the way], the most expensive—of its kind. ▪ Incidentally [=by the way], I saw Susan yesterday and she asked about you.
▪ The report discusses the problem only incidentally. [=in passing] ▪ Not incidentally, the market slump was followed by widespread layoffs.
