Ha, looks like we were both researching cape cod style blue prints today! Good Work!
After seeing the square footage of this home, it seems doubtful to me that it could have more than 1 bedroom on the main floor. EM's home had a galley kitchen, central fireplace (which I assume opens in the living area straight across from the front door). The cape cod I am familiar with had the stairs in a hallway behind the fireplace in the living room.
EM's bathroom (the only one) shares a wall with the galley kitchen back near the stairwell I think (center rear of home) but I am not sure if the bathroom had a window). One bedroom rear right main floor (standing facing front door), living room includes front entry and to the right front main floor, dining area was left of front door adjoining galley kitchen.
Since this home was originally built in 1850, I went researching blue prints from that era. There were a lot of revivials of this style in the 30's & 40's. Here is a link to site that has the original blueprint from the 1700's . . . .scroll down about 1/2 page - shows a keeping room with 7 entrances. I think this part has changed - kinda like if you entered the rear entrance as the front door and including it into the family room. Bathrooms were added after these vintage designs.
http://www.oldhouseonline.com/original-cape-cod-cottage/
It would appear that this 1.5 story home has 3 bedrooms. 2 upstairs where infant & toddler found, 1 on main floor. Either 10 & 13 y/o's shared the one bedroom on main or they were upstairs with the living babies sharing a room with dead babies. EM & RR slept on couches in living room & basement?
This family doesn't exactly fit my image of "normal" families when it comes to sleeping arrangements.