Is it bad to visit a cometary for QingMing if it is also a birthday of a parent or relative?

John, you really think too much. There is a Chinese saying Si Zhe Wei Da, meaning the deceased should be respected. So the living people usually go to visit their ancestors and clean their tombs. It's respect.

By the way, we don't say celebrate Qingming Festival. It's a day for us to commemorate our ancestors.