I was asked the question who are usually invited to birthday parties in my country. I said:
"To be honest I don't even remember the last time I went to a birthday party. But when it comes to (the question) who are invited..."
I wonder if 'the question' can be skipped without changing the meaning.
These are more or less idiomatic ways to express that:
But when it comes to the question of who is invited, they...
(note the addition of the word of)
But when it comes to who is invited, they...
(version without question of)
But, as to who is invited, they...
(a more compact expression with the same meaning)
I've changed "are" to "is". The plural version isn't wrong, but it has a more formal feeling that I wouldn't use. Other speakers may prefer "are".
