Melinda is the great-grandmother of Daniel's twin daughters, Angela and Lilith Pleasant, and Jennifer's daughter Lucy Burb. She also has an unused hairstyle which appears to be a more solid version of another hairstyle.
Melinda was deceased long before the start of The Sims 2, and the only indication of her existence is provided by the Pleasant family tree.
According to her SimDNA in SimPE, Melinda's hair was black before it turned grey.
Resurrection tip
This Sim has no character data and cannot be resurrected in-game. For more information, read this guide.