The only slight issue you might have is with Credit Cards linked to the rooms. Depending on how important to you that each couple charge expenses to "their own" credit card. If you are fine with "settling up" afterwards, no worries, but if you want to make sure all of your DD and SIL charges go to their credit card, it can be done. When you do the online check-in, it will ask you (among other things) for a Credit Card number for the room, then it will ask you who can use it. It also has a place to enter a second card, and who can use that one. My mother stayed in the room with my sister's family, and in this way, expenses incurred by my mother (automatic room tips and anything she paid for with her KTTW card) when to her own credit card, instead of my sister's card.
So in your case, you could put your card number in both rooms for you and your husband and then list a second card and assign it to your daughter in one room and SIL in the other room. They will then use their primary KTTW card to make any purchases, and their "extra" card to sleep in the right room.
And you can be upfront about it with your room steward. You aren't doing anything wrong. Happens all the time for various reasons.