How many consecutive hours do they stay in the pen or crate? During the day, probably about 5 hours is the most you can hope a dog can consistently "hold it." You may need to come home at lunch time to let them out for a break.

Do you exercise them and/or make them relieve themselves prior to being put in the crate or pen? Jack Russells are energetic dogs--maybe they need to have more of a chance to burn off some energy before they will settle down?

Do you feed one big meal in the a.m. only, or do you feed two smaller meals a.m. and p.m.? I know people who have fed only the one big morning meal, and their dogs can't last too long without having to go. Try feeding a smaller meal in the a.m. before work, maybe.

Do they have stuff to occupy themselves in their crate or pen? If they're bored, they'll be bad little pups! A Kong stuffed with their breakfast may be just the thing to keep them busy--lots of crate problems are solved by stuffing Kongs in imaginative ways!

Good luck! Hope this helps.