Hi Kathy,
Welcome! And congratulations on your impending arrival!!
Please have a look at the menopause protocol here:
http://www.asklenore.info/breastfeeding/print/induced_lactation/protocols4print.htmlYou'll need to get started ASAP. It's lovely that your sister has breastmilk available. As long as she's healthy, there's no reason not to use it until your own milk comes in.
It will take about 60 days on the meds before you can start to agressively work to bring in your milk supply. During that time, you can start breastfeeding when your baby arrives with the help of a supplmenentary feeding system such as a Lact-aid
www.lact-aid.com filled with your sister's milk until your own milk comes in and afterwards until it is well established. Once the 60 days are done, it would help if you can pump after most feeds to further stimulate milk production.
Start with this information and let me know if you have further questions or concerns and please discuss all of this with your doctor.
Best,