I can't imagine that this could be resolved in any way other than mediation.

In the absence of any other agreements, the founding statements, both the original and amended versions (Ck1 and CK2) hold sway.

These are pretty unambiguous. There is a section for each member and his capital contribution is stated in monetary terms and then as a percentage of the total capital contribution.

Essentially what you are saying is that each member signed his section of the amended founding statement, thereby indicating his agreement with the analysis of the contributed capital, but then later on two of the three members decided that it was actually incorrect.

In the interim, annual financial statements would have been prepared and the accounting officer would have (or should have) prepared a certificate of members interest for each of the initial members. What do these documents say? Secondly, from whom did the third member acquire his interest, the initial members or from the cc?

As for amending the founding statement; the registrar will not amend the founding statement unless it is signed by each of the members. It's as simple as that, (unless a member is removed by court order, which is another issue entirely).