Parent ID

Parent ID - This field is used in ACR, ACP and Commodity to provide a "consolidated" view of risk. When you assign a Parent ID each "child" will show as a consolidated view when inquiring on a parent. This feature was added to address a combined risk position when inquiring upon the status of multiple accounts for the same company / customer. 

Open

In Grain, you can see all the AR and AP details via customer summary.
If I have 3-names that are child to a parent name ID, I can look to grain customer status inquiry and see how they are in grain-ACR - ACP outstanding balance amounts.

 Example:
Farmer Fred
and the sub accounts for split relationships or joints partnerships, I mark with Farmer Fred's name.
Then I should be able to pull up an all-inclusive look at their position stats by looking at Farmer Fred's account.
Via grain > Status inquiry
You have to turn on security to view it via GRN > Customer Status Summary

Open

And you can run Name/Address reports using the Parent ID as a sort to get grand total AR balances and credit limits.
This is the standard Name/address report, subtotaled by parent id and filtered by parent id (screen 3 of filters)

WARNING:

If the Parent Name ID field is blocked to you at time of editing the General Information, that is because this name IS a parent name id.
It is already assigned to another name/address as a parent.