Relations in drawing BOM

Hello,

I am using multisheet drawings and would like to automate few things in drawing BOMs:

On first page (pic2) of each assembly there is a BOM with subassemblies (always named "SVARENEC"-maybe here could be done some relation...), parts and normalized things (like screws,...).On next (pic1) pages there are drawings of subassemblies.As last there are drawings with stand-alone parts.

I would like to make connection between &sheet_number parameter (pic1) and the collumn "List/Norma (in this case 3rd row) but only in case o subassembly. In case of stand-alone parts the field should remain empty and for normalized parts there should be a norm in that field.

So far i fill all parameters except the norm manually (parameter shown on the pic3).

Thanks in advance

Tom