Sử dụng một nguồn cụ thể trong The Graph Client

i have 2 sources, uniswap v2 and v3, they both share similar fields, but also have different ones. So for example both sources V2 and V3 have a "Swap" schema, but only V2 has the from field, so when i now try to get a swap and the from field, i get an error because V3 doesnt have that field. So how can i tell the execute function from the graph client to pick V2?