To simplify the problem i have

a cars table

a parts table

a groups table(to serparte parts like springs, shocks etc)

and a parts for cars table

Now on my layout(cars table) i have a portal(partsforcars table)

But i want to filter the portal so that it only shows certain parts based on the group ID.

i have made another table occurence called filteredpartsforcars and i have the realtion ship joint by filterkeys (groupID), but my portal is showing no data?

does anyone have a similar problem or know how to solve?

It would seem to me that the GroupID, on the "left", or originating side of the relationship, in Cars, would likely be a global field, so that you could switch it to see the parts you wanted to. Or, it could be a regular field, so that each car would have its own "choice" of group.

But what you're doing should work. Each Part would have to have a GroupID, foreign key. The Group table in this case would be mostly used as a reference table, to hold the groups to use for a value list to use in Parts.