What do you think of Meg as a nickname for Margaret?

I am pregnant with twin daughters and we decided to name one after my husband's grandmother,Lily. We have intent to name the other one after my grandmother, Margaret, but I also have a sister named Margaret who goes by Margaret so we were thinking of calling her either Maggie or Meg. Currently, we think we like Meg more than Maggie. What do you think? Also, which sounds better Lily and Maggie or Lily and Meg?