notsorryforpartying

I've got a niece (5) and nephew (3). The niece is really good about finding ways to entertain herself and the nephew will always try and take it for himself and intrude, usually not in a compromising sort of way. Obviously, this is pretty typical kid behavior overall.

She's reaching the age where she can learn more complicated games and ideas, which sounds really fun to introduce her to. If he's around, I feel like it will certainly cause a meltdown, and he's too young to reasonably participate anyway.

As an older sibling myself. I think it's also unfair to hold her back until he can participate too. Some would say it's unfair to do it until he can as well. I would argue that it's actually unfair to introduce 5 year old games to her when she is 7 and he's 5 and can join too. She's being punished imo unnecessarily and being held back. Why does she have to wait till 7 while he gets it at 5?

Is the only solution to try and schedule separate activity times to individualize the activities? Am I being biased as an older sibling myself in feeling that I would be holding back until he's at the same capability? Just curious for feedback. Thanks