Simon Cowell thinks his son will marry his ex-girlfriend's daughter.

The music mogul has stayed close friends with Terri Seymour since they ended their six-year relationship in 2008, and his two-year-old son Eric is ''madly in love'' with the 'Extra' presenter's little girl Coco, 21 months, who she has with boyfriend Clark Mallon.

Terri said: ''Eric and Coco are madly in love with each other and Simon is convinced they're going to get married.

''Eric calls Coco his girlfriend but they're having a long-distance relationship.''

And it seems Eric - whose mother is Simon's girlfriend Lauren Silverman - already has competition for Coco's affections.

Terri added: ''It's funny as they're apart so often as Terri spends so much time in the UK, but he's also very loyal.

''Coco on the other hand isn't so loyal and has another little boyfriend called Henry, so Eric had better get back in the picture as Henry is moving in there.''

Despite her history with Simon, Terri gets along very well with his girlfriend.

She said: ''Lauren is a really good friend and we've become very close. She's one of my best friends and we speak all the time.''

And the 42-year-old beauty wouldn't be surprised if the couple have more children.

She told Closer magazine: ''Having Eric has completely changed Simon.

''He's an amazing dad, very hands on and completely adores Eric.

''I wouldn't be surprised if he has another one soon.

''I think it would be good for him to have a little girl and for Eric to have a playmate. He has Coco but it isn't the same as having a sibling. I'd say watch this space.''