It's so hard to have a baby these days. You need all the help you can get. When this mom to be wants her SIL to be her surrogate, she asks Reddit:
My husband and I have been trying for pregnancy for years now, and to cut a long story short it seems as though it will never be a possibility. It took a long time to come to terms with but we've gradually got there.
Our entire family is aware of the journey we've been on and how much it meant to us. With that in mind, my husband and I came to his sister (Sarah) with a proposal.
Sarah is in her early 30s, unmarried, and vocally against having children of her own. Despite this we thought she might be open to the idea of a surrogate pregnancy on our behalf given she would not have to be involved in raising the child personally.