Can you assign a recommender after the submission deadline?

So this school on the Common App has an option to assign an additional recommender. I did not know of this, so decided not to bother with the recommendation one of my research mentors wrote. Is it ok to assign him as a recommender after the January 1 deadline for this school or should I just forget about it?

Don’t forget about it everything helps! I did the same thing and ended up calling the schools I was applying to. They told me to just send their recommendation directly to the admissions office and they would attach it to my application, so I would say to do that.

It’s just that the college would see when I would assign the recommender, and if they see that I assigned it after the deadline, would there be an issue?

Bump!