Star magazine reports that the 49-year-old music star has countered the German supermodel's request for primary physical custody and wants to ensure that they both get equal time with Leni, eight, Henry, six, Johan, five, and two-year-old Lou.
And the British star, worth $15 million, is also said to be contesting Heidi's claim that they did not have any joint assets that need to be divided up. The 39-year-old Project Runway star apparently has a net worth of $70 million from her modeling, endorsement and TV deals.
It's also reported that Seal used intimate pictures of the children in an advertising campaign for Leica digital camera without his estranged wife's agreement which caused some friction.
"Heidi felt that the children had gone through enough since their parents split, and she didn't want their private moments out there for the world to see," an insider said.
"But Seal maintained he had every right to use his personal photos - and, moreover, that it was a done deal and out of his hands."
The image was taken down within days after Heidi got her lawyer on the case.
"Heidi isn't trying to cause trouble," a friend told the publication. "She's just trying to protect her brood. Since she filed for divorce from Seal, he's been out with more than one young woman, whereas Heidi hasn't dated at all."
There had been reports that the blonde beauty was dating Germany's Next Top Model executive Thomas Hayo but she has denied there is a romance.
"She's not interested in beginning another relationship right now," the insider added. "Her primary goal is getting the kids through the divorce and making sure they are healthy and happy."