In principle, it is necessary to decide: should the clan rating be considered as a single entity (in which case all versions are taken into account) or as the sum of the players' ratings (in which case it is calculated separately for each version)?
And besides, the formula for calculating individual ratings is also a controversial point.
The individual rating (i.e., the rating for a tournament) is calculated using the IronAxe or AmberSoler system.
And again, there's a snag: let's say we sum up the results of 4 players to find out the clan rating, for example, in the 5th game.... and I'm not sure that all clans will have 4 people playing at a tournament level in the 5th game; the same situation applies to other versions.
Firstly: there is no problem that you mentioned.
Secondly: all members of the clan contribute to the cumulative rating.
And finally: the condition for the average rating does not encourage the presence of "dead souls".
Sincerely.