He and Jan didn’t work in the same office. She was in NY and he was in Scranton. I’m guessing that’s why.

How come Holly was allowed to date CJ?

I always thought it was because Michael and Jan's relationship ended so badly, and they sued the company...so Wallace wanted to avoid that again.

Michael is Holly's superior and they didn't disclose it. Holly is HR and AJ is in sales, and they probably filled out a form.