My sister offered to my egg doner and gestational surrogate.

My husband and I have been trying to have a child for 4 years. After a traumatic 3 years of fertility treatment and ultimately, learning that pregnancy would be nearly impossible but also very dangerous for me, we decided to stop ttc. My sister got pregnant and had a beautiful, perfect baby girl. She's a year old now. And my sister has been offering to have a baby for us for some time. My husband and I have been going back and forth about whether or not we wanted to pick up here we left off with treatment and try to have our own child. But it's just not worth risking my own life. I'll be having a hysterectomy in the near future. But my sister brought it up at our Thanksgiving dinner today. And she's serious about it!! I'm speechless. I just can't believe someone would be so selfless and generous. I think we're going to go through with it. We've wanted to be parents for so long. And this might be our chance. Is there anything I should know? Where do we start? Any surrogate mothers have any advice?