Hi Claudio,
FM document is always created for combinations 30/2 and 30/3. Whether it consumes the budget or not, that's already another issue and will depend on the settings of update profle, tolerance profile, 'statistical' CI, etc. If by 'balance' you mean totals, then the answer is yes: it will be updated both in AVC ledger and in FM totals (FMIT). There are ways to skip updating AVC ledger, though. But, totals (FMIT) should be always in line with the documents (FMIOI/FMIFIIT).
I'm still puzzled that some of your interfaces could be impacted from creation of FM document, unless these interfaces are somehow linked to incremental monitoring of FM tables, which would be a bit strange. In any case, all these 'undesired' effects could be filtered out both from reports and from interfaces with simple variants.
Bottom line: certain FM process, like payment transfer or others, require creation of FM documents. So, you have to manoeuvre between this fact and a wish to skip FM documents creation.
I hope, it clarifies the issue...
Regards,
Eli