"Partner Determination Steps for Customer Master" clarification

Question

Hi,
Let me clear myself at the outset itself, that I searched SDN for my below mentioned query, however I could not find any answer to my satisfaction....here I am posting again
In "Partner Determination for Customer Master", the following steps are undertaken -
Step 1:
1.a.) Create New Partner Determination Procedure 
1.b.) For each Partner Determination Procedure, different Partner Functions, which are applicable for that specific determination procedure, are assigned. (along with other properties like if the PF is mandatory, not modifiable )
Step2:
"Partner Determination Procedure Assignment", here we assign different Partner Determination Procedure to different Account Groups. In other words, indirectly, we assign the partner functions to account groups. Right? (Please correct me if I am wrong)
Step3:
"Partner Function". Here we define new partner functions, (which are used in Step 1...)
Step4:
"Account Group- Function Assignment" - Here we assign the Partner Functions to Account Groups
Now My Question
(A) Since the Partner Functions are assigned (via partner determination procedure) to account groups in Step 1, then why Partner Functions are assigned AGAIN to account groups in Step 4. What is the significance of this assignment in Step 4.
(B) Is there is particular sequence of Steps (1 to 5), one should follow when somebody has to create new customer account group and/or new partner function.
Thanking you all in advance.

Answer 1

Dear SR
Leave SAP Partner Determination screen for 2 minutes and first understand the logic
1. Create the new partner functions
2. Create the new determination procedure
3. Link the new  partner functions to the  new determination procedure and add mandatory, non modifiable ,optional creteria
4. Assign the new  determination procedure to the document type or account group at appropriate level
This is essence and this is for all  8 levels like CMR,sales doc header,item etc
Now coming to your qn
When you define a new account group ( you might be aware account group controls partner functions of CMR) you will say that your  new account group  will carry out patner functions like SP,SH,BP,PY
That is ACCOUNT GROUPS  function assignment
Whenever you create a new account group  you will do field selection in OBD2 like suppress optional.reqd etc,create no ranges and assign no ranges and also mainly this activity partner determination
These are must settings for a new account group
AG is the german key for sold to party Partner determination procedure
This is step 1
Then in next step you will tell AG will carry out such and such partner functions Step 2 like mandatory not modifiable etc
Step 3 is link the AG to your account group
Step 4 is partner functions say if you want to create a new partner function say SB special stock partner
(in concept this is the firststep)
Step 5 is once again partner function account group  assignment
So when you create a new partner function you will do step 4 first and step 5 and then 1 and 2 and 3 
when you create a new account group you will do step 5 and then 1 and 2 and 3
Hope you understand now
Partner functions are relatives in your family
Say in a family we have Father ,mother sister, brother (these 4 partner functions)
This is called as Happy Family  and this Happy Family  is the Partner determination procedure in SAP
This Happy Family  is linked to the account group
So Happy family means there are 4 partner functions
So whenever you create a CMR in the account group this father.mother,brother,sister will come as default
Suppose you add another partner function say Uncle
First you have to create uncle
Then you have to tell this account group will accept uncle
Then link the uncle in the happy family that is determination procedure of SAP along with the 4
Then assign  happy family  to the account group
Now when you create a CMR along with father.mother,brother,sister  along with that uncle will also come
Regards
Raja