That would be confusing:
"This is Andy, or Chis Maj., as we call him. And this is little Jimmy, whom we call Chis Mi or Baby Chis. And this is Ross, whom we call Chis Andy".

Eton apparently traditionally went for Major / Minor / Minimus, but only if all three were there at the same time. So I think we can safely stick with Chis Maj. and Chis Mi.

I remember once seeing all three playing at the same time.
But - Chis Minimus has a nicer ring to it than Baby Chis.

Thinking back on the game, one thing worries me: On-field leadership during the game. While I'm happy that Gussy was able to read them the riot act at halftime and get the performance, he shouldn't have had to do that. The on-field leaders (Robshaw, Chisholm minor*, Smith, etc.) should have been already getting their teammates to up their game during that first half. Against better teams, we would have shipped more points in that first half & had a harder job coming back to win. In years past Robshaw would have been rallying the troops as soon as we went down to 14. Whether his mind is already a quarter of the way across the Atlantic, it seems these last few games he hasn't been able to inspire the sort of team performance that the game requires. I'm not saying he's slacking off, just that Gussy needs to look at the on-field leadership core & get them more prepared to rally the troops in adversity.
What about calling Ross, Ross and James, James.
Don't think there can be any confusion with that!


*Quick point that I may have raised before: James Chisholm should actually be referred to as Chisholm Minor (Chis min.), with Ross being Chisholm Major (chis maj.) Senior and Junior is normally used to refer to Father and Son, not elder and younger siblings.