TDD specific query

Hi there

I would like to know when it comes to TDD (Top Down Distribution in COPA), when we have COPA derivation rules preset already.

a) when FM module is active where we would also have set up the FM specific various FM derivation rules;

b) when we have IO Internal Order settlement distribution rules preset,

finally, when it comes to TDD at month-end closing, which one takes priority - IO settlement rule or FMDERIVER preset? I suppose it's IO Settlement distribution rule would prevail over any other, right?

c) additionally, every time we modify the distribution rule in IO (Internal Order), it gets stored in CE4*** tables with a revised / current posting date (i.e. date of each such change). This posting date, does it have any impact on monthly IO settlement and/or the TDD ? Reason to ask this is, say if we have a settlement run date / TDD run date as 30.09.2022, if we have a distribution rule modified in Oct 2022 (before actual Sep 2022 closing), when we run the settlement or TDD with an effective date 30.9.22, will the TDD pick up the modified distribution rule, with a later posting date precisely? I suppose NO. Just checking to reaffirm my understanding.

Excuse my ignorance here. Any clarification would be of great help from CO Experts.

Cheers Siva