I think Emily was planned to be a much bigger character on Friends but the actress was pregnant and couldn’t commit to longer filming in the US. It’s why she’s shown in bed when she and Ross are having the discussion about him never seeing Rachel again
I read the role originally was offered to Patsy Kensit but she turned it down, I think she would have done the role far more justice than Helen Baxendale who came across so hard and brittle, mind you I’ve never rated her in anything to be fair.