Sorry to be annoying, but really appreciate getting outside opinions on this one.
I agreed with the comment in my original poll about having only one boy in red would stand out too much. So two more options:
Option 1 (little one would wear plaid shirt, 4 year old train shirt w/red vest)

Option 2 (little one would wear train shirt w/red vest, 4 year old train shirt w/red shirt showing beneath)

In all options, both boys and DH will be wearing jeans so not going for a super formal look.
[Poll]
Thanks again!!!