Hello and welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
From your medical history ,i can deduct that your sister has the TORCH syndrome.
This may sound like a single illness, but actually it stands for a group of infectious diseases that can cause problems -- some serious -- for the unborn baby.
If a woman get one of the TORCH infections while you’re pregnant, and it spreads through your blood to your baby, he can get it, too.
In these case it is necessary to treat the infections and only in the moment when the specific infections are disappeared ,it is safe to conceive.
My advice for your sister is to consult a local
obgyn for the right treatement of her actual infections and the advice when she can start traying to conceive again,without riscs.
Hope this is helpful.
Take care