Personally, if he's already getting hassled by a bengal mix then I wouldn't introduce a bengal. Bengals are typically quite high energy cats and they play VERY rough. When my two were younger I was never sure if their playfighting was actually play or whether it was an actual fight.
If he's not a particularly high energy cat and doesn't like being hassled then I wouldn't think about a bengal. He will be the bengal's replacement littermate and therefore plaything. And if the kitten is anything like my two, it will be relentless if it wants to play with him and he doesn't want to play with it.
On top of that, if your parents will be working long hours, then Marmaduke is going to be the only thing the kitten has to play with, with no distractions to divert his attention. I'm sure he'll have toys left out for him- but moving targets are always a lot more interesting than stationary ones. ;)
That's just my own personal opinion anyway.
Edited to add: just noticed this was your first post- welcome! we expect more photos of your critters, please. It's a mandatory requirement of being a member of the forum.