Mel's younger sister Danielle told British OK! magazine that they fell out two-years ago over her opinion about her producer husband Stephen Belafonte.
The 30-year-old, who lives in Surrey with fiancé George Lee, daughter Mimi, three, and baby son Hendrick said: 'Our family had concerns about her husband Stephen. Ever since we expressed those concerns, we've not heard anything from her.
'I just hope I will speak to Melanie again because she's my only sister. I miss her and my nieces ridiculously. It hurts.'
Danielle also admitted she checks her 35-year-old sister is doing well by following her on social networking website Twitter.
She added: 'I don't think she even knew I was pregnant. I don't even know if she's aware I had a baby. There have been six babies born in our family in the last few months so she's got these six additions to the family that she doesn't even know about.
'I don't have her number, I don't know where she lives - I wouldn't know how to get in touch with her. I follow her on Twitter to make sure she's OK.'