Here is the layout, forgot to add it to the post

It is incredibly rare for moving a stair to be cost effective.

You’re taking a 300K remodel and making it a 375K remodel. TV shows are not documentaries. It’s all fake timelines and fake budget and fake drama.

Would you consider instead creating a second small laundry area in the new master addition, if your goal is to have a laundry closer to the bedrooms?
I have two laundries. One upstairs, front loader, adjacent to the master. One in the garage, top loader, for work clothes, rugs, camping clothes and bedding, bulky items, etc.
You're running plumbing lines, anyway. to the bath addition. Maybe use part of the existing closet?

I agree that moving stairs is a huge issue and IMO not worth it in your case.It makes perfect sense to walk in from the garage and either go down or int the main floor.Since you are adding on for the master why not think about the laundry near there instead

thanks all for the comments. I was thinking it wasn’t worth it as well but wanted to explore all the options. I considered laundry in the addition but I know that it will end up in baskets & piles in the bedroom. I’d rather have it in its own room where I can shut the door on it, etc. Also, when the kids are older they won’t have to go through the master to do their own laundry.

I’d try the bathroom where the bed is now. Don’t care for how it’s boxed out in the corner of the room. That plan needs reworking in the master area to me

I think i’ll do another post on that...that was consideration but we thought it would make the entrance tight and the front faces a busier road, but we are set back and up. But, we would be able to just run the plumbing straight up from the basement rather than under the addition. Further thought needs to go into the addition for sure. Thanks!