Thanks thomas, i've started to find how the filter works but i found in several forums that the filter property doesn't works for memdataset, i can't find any clear source on how use the filter property. I think that it should be something like "id = 16' but doesn't worked, then read in some forums that filter doesn't work memdataset, but they work in bufdataset.
So dropped a couple of bufdataset on the form, created the fields in the fieldefs with the same fields i used on memdataset (double checked it), then linked it to the respective tfrbdataset in the form, but when i try to set active=true in bufdataset in the designer it gives me "Missing (compatible) underlying dataset can not open"