[quote=@Sini]

If all the Tyrells had but one neck...
[/quote]

They've been very lucky so far. It'll only take a second to change that, no doubt they'll find themselves in the thick of it.

I've put up a vague list of ages and so on, it is mainly how to explain how Alestair, Garland's cousin, is older than him whilst being born of a thirdborn (in this scenario, it seems that a good bunch of the Tyrell bunch had their kids late).