EXCLUSIVE: Palin Camp Lashes Out At Levi Johnston's Sister; Says Blog A Front For Palin Hate Group

The Palins might have Levi back on the family train, but there's a rogue Johnston still stirring up trouble in cyberspace.

Levi's sister, Mercede Johnston, has started a blog in which she promises to answer all questions related to the Palin family.

One of her claims is that her brother and Bristol Palin planned to conceive their son Tripp.

"During that time period, she and Levi were sexually active and trying to conceive a child," Mercede wrote.

"As hard as it is for many of you to believe, they were indeed TRYING. It was NOT an accident! Also there were a number of rumors circulating around that she was already pregnant."

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But a source close to both Bristol and Levi told RadarOnline.com exclusively that Mercede's shocking claims are completely false.

The source also claimed that Mercede's blog is being backed by well-known Palin hater, Jesse Griffin.

Last year, Griffin was unmasked as the writer behind the handle "Gryphen" -- the publisher of a blog called "The Immoral Minority".

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He is a part-time teaching assistant at Trailside Elementary School in Anchorage

"Mercede was put up by Jesse Griffin to do this blog," the insider told RadarOnline.com exclusively.

"He is a Palin hater and is most likely behind the comments."

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The Palin source continued: "Levi would never confirm or comment to something like this and neither would Bristol.

"Mercede's claims have been contradicted by her own brother's public statements.

"Levi has said always said that Bristol's pregnancy was an accident."

As RadarOnline.com was first to reveal, Bristol and Levi have mended their once sour relationship and have begun working together to better co-parent their infant son Tripp.

19-year-old Bristol Palin told RadarOnline.com, "Levi and me are co-parents of Tripp and we are actively working on being good parents together."

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The pair had an acrimonious break-up, soon after Bristol gave birth to Tripp.

Levi went on a publicity campaign lashing out against the former vice presidential candidate.

But now all appears to be forgiven. Said Levi: "Nothing is more important to me or Bristol than our son Tripp. We are taking active steps to work cooperatively in raising him and in sharing the joys -- and challenges -- of parenthood."