Got the idea of what if Mheetu was Nala's cub, not her brother >> How would she break the news to Simba?
After all, she may have fallen in love with him in the jungle, but she hasn't seen him in three or so years, so I doubt even Sarabi would know how he'd react to Mheetu...
Especially if Nala where to tell Simba who the father was >>
But in Nala's defence, she DID think that Simba was dead, you can't linger on someone who's meant to be gone, you need to move on ><