Jibini and I have moved probably 8 times in the 8 years I've had him (and we're about to move for a 9th, and hopefully FINAL time.) That's not counting the times I've switched trucking companies or had to move from one truck to another.
The first couple of times I think it was harder on Jibini….more confusing. He visibly reacted with increasing levels of stress as we removed more & more furniture from the house. He was crated as we were moving out of the old place- so he had to sit & watch as we carried out all of "his" stuff- but not HIM. I don't know how much dogs truly understand....but Jibini IS normally comfortable in his crate. But he had a FIT when we were moving. He also immediately calmed down once we took him & his crate, and put him in the car. Still crated- but he was WITH us- and so he was OK. Once I started trucking with him & he got used to the fact that he ALWAYS comes with me when I go somewhere, he reacted much better to the whole ordeal. As well-traveled as he is at this point, he is rather blase' about moving now
The fact that you're keeping her at your in-laws' place may help....I would definitely avoid exposing her to the whole "They're taking all my furniture but they're not taking ME" process. Maybe she can stay there while you're moving stuff too- until you get the furniture moved & set up again?? Maybe it will help make the adjustment period easier if she sees less of the moving OUT process, and the first real "change" is the first visit to the new place, filled with familiar items.
Definitely place familiar & favorite items of hers throughout the house- I would also reccomend trying to arrange for at least one person to stay home with her the first couple of days. Frequent walks around the neighborhood are a great idea so she gets used to her new surroundings (and don't forget to have her ID tags changed!) Frequent trips to potty outside- pretend she is an 8 week old puppy for the first week or two, will help minimize accidents. If you give her EVERY opportunity to go outside for potty, you'll be suprised how quickly she figures out which doors lead to the yard!! These are Basenjis after all- escape artists- the only breed of dog that can come to a new place & spot a hole in a fence from 600 yards away. She'll figure out where "outside" is for sure.
Been a while since I've had cats, but when I was a kid & we moved, I never recall them having any accidents. It seemed like all we had to do was put them in the litter box once or twice, and they remembered. Maybe it will be better than you expect!! Best of luck to you all!