AVC Ledger derivation

Good days gurus,

My client has a custom AVC ledger (Z1) and we want to prevent GM budget documents with of a specific type (XX) from being posted into this ledger.

I thought of doing this through the derivation rules, but we are unable to have the field GRANT_TYPE from table GMGR in the set of tables available so we can create the condition to exclude grants with this value.

Does anyone know how to include this table so we can create the AVC derivation rule?

Does anyone know of any other solution using only grant_type as a mean of evaluation?

Thanks.