IMO a main floor laundry is so much more convienent and the issue you have would make it a real PITA . Is there not a way to reconfigure the space you have now to do both jobs . I have had basement, top floor and main floor laundry and give me main floor everytime. One trip down with dirty and one trip up no running up and down to load washer and dryer.Why do you need an entry from the deck to the laundry at all. I can see a couple of ways to reconfigure what you have if you can post the sizes of those spaces that would be helpful

I can see where having all your bedrooms upstairs where most of the laundry is created save for kitchen towels and some other random items are. I had a upstairs laundry in my last home where all bedrooms were located and it was wonderful to not run up and down the stairs with laundry. How large is the the bedroom directly above existing laundry? It looks like the natural plan (seeing as plans called for an additional bedroom in attic space?) would be to continue the hallway cutting off a portion of bedroom number 4 to gain access into the attic space to create the laundry. Moving the bedroom door to right outside bathroom.

@Patricia Colwell Consulting Thank you for your input. The current laundry room is 9.5 x 6 ft. I think the door was an entry from the deck before it was enclosed as a screened in porch. We never use it and would consider removing it. I worry that the space isn't quite big enough to combine functions but would love to hear any suggestions you have!

@Design Interior South Thank you for responding. I have considered what you suggested before and it's not really clear from the floorpan that I posted, but doing that would pretty much eliminate my daughter's walk-in closet. I just couldn't come up with a good way to access that space and keep her closet intact. I have also considered just moving and stacking the washer/dryer in the linen closet outside the master, but I don't know if it's a great idea to eliminate a decent sized laundry to put it into a closet. Here's a quick modification of the floor plan that shows how it impacts her closet.

If you close off that door then the W/D could go against the wall where the door was .