We have a 12 week old kitten who didn't pee for almost 24 hours. She then decided to pee in the bin with the news papers and there was a big amount. She had a sister that passed away this week from an intestinal disease and I am wondering if she is missing her. I have put her litter box downstairs and am wondering if she needs one now upstairs. I guess I am a little nervous because the other kitten died. Any help is appreciated.

Yes multiple litter boxes will be helpful, was she on the story of the house without a litter box when this happened?
She may feel a little stressed from her friend not being there.
But if she continues with this behavior I would get her in to the vet sooner rather than later.

Yes multiple litter boxes will be helpful, was she on the story of the house without a litter box when this happened?
She may feel a little stressed from her friend not being there.
But if she continues with this behavior I would get her in to the vet sooner rather than later.

Thank you for your help, I have put a little box upstairs and she is peeing but only in little amounts (the amount last night was very large) She is still eating well and active. Should I take her to the vet?
There is no sign of blood or anything so I am wondering if she has a mild infection.

Frequent and small amounts of urine can indicate a urinary tract infection. You may not see blood in it.
If she is making frequent trips and only producing small amounts or no urine then it would be advisable to have her checked.