graphic legend for seating section

[Ben3B]

Hello I have a seating section with round tabe and chair 

 

I would a graphic legend who reports the symbol used by seating section ...

I can't find the good setting in criteria in define custom source ...

 

the only way I've found is to set criteria by symbol with contains table, with plug'in checked ) 

 

but If the symbol doesn't contains table it will not work and if I ve another symbol with table it will appear ... (ok ok can filter by layer and by viewport ...)

 

At the beginning I tried by Type is seating section 

I seek for symbol used in that seating section but I don't found it ... is it a good way or I'm wrong ?

 

What is the way for the graphic legend report to the symbol used in seating section style ?

 

Thanks!