Splash isbar X chicks hen or roo?

[Venusserena7]

I know they’re young and it’s hard to tell but I feel like there is a clear difference in the tail feathers. Any input?
Back story:
I have four of these chicks, all the same age. Only one has these short fluffy tail feathers. I also have two older barred Plymouth and one Red sexlink

 

[featheredplanets]

Unfortunately tail feathers are not an accurate way to sex. Best bet is updating with pics of their combs when they’re at least 6 weeks old.