Omit Shir Hamalos before Bentching at Seder

Some have this Minhag, (but Shir Hama'alos is not such an old Minhag, so you can't really find too much about it in the Seforim). The reason they give is because Shir Hama'alos is said as Divrei Torah at the table, and on Seider night we say a lot of Divrei Torah at the table anyway (the Haggodoh), therefore there is no need to say Shir Hama'alos too.

Michael FRSBH