What we are witnessing is exactly what our Founders and Constitution sought to prevent: An impeachment of a President solely for political gain. Prove this and then end it.
One more witness does not support "fairness"; it supports the further weakening of the US Constitution by both Houses of Congress giving credibility to something that has already earned its place in the dustbin of our history. Joe Biden is simply not important enough of a reason to risk further damage.
This impeachment is not about Joe Biden or his son; it's not about Ukraine. It is now about ending the separation of powers unique to our form of government by permitting the abuse of Congressional power to become sacrosanct.
If the President's attorneys do their job fully they will present a case to not only fully acquit the President of the charges against him--but to sufficiently set up the next final and critical stage in this drama: An independent counsel's investigation into the activities of the missing fact witnesses: Adam Schiff, Nancy Pelosi, the "whistleblower" and his/her accomplices.
Do this and save our form of government.
Let the voters handle Joe Biden.