He decided to take Max back to Alice's room, and have her in place to do something. Once he walked back in, he asked...
"Hey Max. Want to go on a little trip?" Jeff sat down on Alice's bed, carefully pulling Alice out. "Huh? W-what kind of trip?"
Jeff smiled, before glancing at Alice. "Well... Inside of her. I think it could turn out fun." Max looked a little red, but responded. "A-Alright..."
"Great, let's do this..." Jeff pulled Max out, setting him between Alice's legs. Trying to line him up, Jeff pushed Alex against her privates, his head slipping in easily; Max let out a gasp of surprise.
He continued to push his little brother inside his sister, while taking off his clothes in the process. He left Alice's diaper on her bed next to her, and soon, Max's entire upper half was inside Alice's vagina.
Jeff leaned up, taking Max's penis into his mouth as he started pushing a bit harder, following Max inside. His hands were pushing against Max's legs, spreading them apart, but this soon didn't matter.
Max's legs were closed together due to the side of Alice's opening, raised up; His legs kept Jeff's mouth around his genitals, unable to move as his butt was below.
Jeff pushed on as far as he could, the walls contracting around him. It was tight, so he couldn't do anything to move his head out of this position, but he moved as well as he could.
Soon, he could feel a bit more resistance, as well as some sounds from Max. Max seemed to be a bit harder, and each movement was also influencing the walls around them. He pushed forward, as Max went through Alice's cervix.
The hardest part was getting Max's arms through. Once the arms were in, it sped up a bit, as Max quickly filled into her womb. The cervix pressed hard against Max's legs, and as a result Jeff's head, as he himself started to enter...