Basement Window-Fill In?

Basement Window-Fill In and vent positioning

I plan to start slowly remodeling my basement bathroom. There is a window in the bathroom, which takes up considerable wall space above the sink, making mirror placement nearly impossible. My wife wants me to fill in the basement bathroom window.

I'd rather not, but we also plan to put in a single patio door out from the floor above the basement window, so the window will be covered by steps at some point anyways.

I've attached a picture from the outside. The window above the basement window is what is planned to be replaced with a single patio door.

Any suggestions on what I should do? I could fill in the window with some concrete, but any suggestions for why I should not?

Also, you will notice in the picture the bathroom drain vent, is that going to be a problem when there are eventually steps nearby? I will also need to install a bathroom fan vent in that area as well.

Thanks for any insight.