Leas carrier box I got from the event is clean now I just need a box for the new kitten.Also lea has all her shots I have her papers somewhere in my desk.yeah the new kitten doesn't have a carrier I'm just going to use a box low on money from all the cat stuff I've bought this past month.
If she is only 9 weeks old, 8 when she came home with you, this is not possible. Kittens have to have series of shots, and the rabies vaccine is not given until at least 12 weeks. At the most she will have only had her first FVCRP and possibly her first FeLV.
Follow up visits for the remaining shots in the series would have to be scheduled. The only reason this matters right now is that she is NOT protected from anything the other kitten may have.
I hope you will return Lea today. The sooner she is brought back, the less stress she is going to suffer, and the better her future will be.
If the carrier belongs to you, when you bring Lea back you will keep the carrier. If it belongs to the shelter, of course they will keep it and you should get a new one for the new kitten. A "box" is not adequate or appropriate, you need a secure carrier specifically made to carry pets.
Once Lea is returned you need to get the new kitten to the vet right away. She needs to be tested for diseases, FeLV, FIV and heartworm. She needs to be de-flead and de-wormed or your room will soon be full of fleas. And she needs treatment for that URI, and to make sure she isn't pregnant.