Diana,
Well, the problem is that we on this forum do not know your data and the specific details of your requirements. So what I am saying here may or may not be helpful. As you probably know, g/l account maintenance is where you tell JDE what to do about subledger information. The posting edit code is the field that controls this. So the question is this - do you have g/l accounts that have a mixture of subledger types in them? Maybe some do. Many may not. For example, usually you have work orders being charged to g/l accounts that only have work order activity in them. So for those accounts, you may (if you really, really want to do that) set the posting edit code to "X" (no subledger entry allowed). If a g/l account does require a subledger value on every entry, posting edit code "S" would seem to say to post in the F0911 that way, but not in the F0902 (though I have not personally done this, so cannot vouch for it), and since the F0902 is your issue as I understand it, you could try this on accounts where you know you won't have address book type subledger activity.
Chances are your accounts currently have a blank posting edit code value, correct? Which means subledger posted in both F0902 and F0911. Sounds like you need a new posting edit code that is kind of like "S", that allows (does not require) sub ledger entry, but posts subledgers only at F0911. Sounds like you need to submit an enhancement request to Oracle for this capability. Maybe your company would consider paying Oracle to create a modification for you that would then go into future versions?
Now, I am not familiar with A9 (just 7.3), so it could be possible something has changed in A9, though I get the sense it has not. You probably would want to log a service request with Oracle support and see what they say on this.
John Dickey