Mmmm from my point of view NurKasih, I think its better that you keep your cats. Talk it out with your mum and try to come to an agreement on how to keep your cats without affecting your sister. I am sure that there is a way. Masa I pregnant dulu, my mum in law and my mother asyik asyik menyanyi asking me to give away my cats (7 of them) as I was pregnant and they said that bulu kucing boleh affect baby tapi alhamdulilah my kids tak ada apa apa pun sampai la sekarang, I tak peduli, I tutup telinga and wat pekak je. I know its not easy but I jenis keras kepala he..he.. Akhirnya I menang juga. Baru baru nie I pun ada menghadapi masalah with my cats because my family suruh I bagi kurang tapi I berkeras juga eventhough they threaten me macam macam. My brother even said that he will come and kill my cats
But I stood my ground and I still have them with me. I tak sanggup berpisah with my cats and I will move heaven and earth to be with them. When I moved from Kuching to KL, I brought my cats and if I have to move again I will bring them with me.
Fostering your cats to someone susah sebab nanti your cats akan bertambah sayang ngan orang yang jaga dia dan vice versa and when the time comes for you to get it back it will be hard for the fosterer to berpisah with the cats, I know I would be he.he...
About giving it away.... I don't think so as you love them very much. I hope and pray that you will be able to reason with your mum and let your cats stay with you!