This is the second time I have answered a question like this today.
When you say appear to be pregnant, have you palpated them? Some rabbits just look fat, it's getting to be cool weather and many of mine have already turned sluggish and put on their winter coats, making them appear thicker.
We don't cross breed Cali's.. period.. not even the NZW's.. so I had to ask for help in this one..
Rabbit's can die from stuck kits.. so that was an inaccurate statement. I have had a Cali doe die from one 2 years ago, and my BF had to remove one of my recent litters stuck kits in January..and the doe was going downhill fast.
It's kinda like removing a bowling ball stuck in a toilet.. just doesn't fit, and not likely to dislodge on its own.. the size differential between a cali and your girls is massive.
To quote directly the advice given to someone else by my BF..
"
I'd take her in for the spay, chances are she didn't take, but on the off chance she did, her life is at risk.
It is much like a tubal pregnancy in humans, the smallest size increase in the fetus could rupture the fallopian tube, effectively sending the mother to surgery where she may never have children again due to the blown tube, except in a rabbit it could kill her.
In a week or so however, you should be able to see the peas in the pod, so if you must wait, wait till then.But no longer"
So in answer to your question.. yes.. it CAN hurt/kill your girls.. but really.. have them X-Rayed to be sure before you go emergency spaying them..
Best of luck..
Z and the Tree