If the source is considered canon, there have not been too many changes. Consider them constraints.
First the list of of who is in the 29 has only changed 10 times. Their strength and power may have gone up or down or broken free or suffered vassaldom, but changes can only result in at best 10 different name changes to the list, 9 given the fact that one was given in the text.
Not exactly -- the exact quote from the CT Alien module is "Of the original 29, nineteen of the original clans remain in it today; the remaining ten positions have been occupied (some by a succession of clans) by new clans which have risen in strength, power and population to replace the others" (5).
That suggests there have potentially been far more than just 10 changes in the history of the
Tlaukhu. Some of those 10 slots have had multiple clans cycle through -- and I would imagine that any new
Tlaukhu member would be very vulnerable to enjoy only a short tenure: they had to expend resources to break into the 29, and all the other clans outside must recognize their best shot at sitting on the
Tlaukhu is to knock off the newest, weakest member.
Further, within the 29 as a whole there has been movement up and down the ranking. As you rightly point out, while the
Tlaukhu is fairly stable, it's not static.
We know that the list in TD18 reflects the situation in 1120, which is the year that the
Hlyueawi clan is cast from the
Tlaukhu by the
Hlaotiyoiho in 1120, and that this change shifts other clans around. So I'm just trying to reconstruct the composition circa 1105.
[Actually, upon review TD 18 does not seem to reflect the 1120 changes, though S&A does.]