We had a supplier come back on a re-procurement contract and "explain" how the part could not be made as they had repeatedly failed to make a suitable weldment.
Their welder was trained in the Air Force for structural repairs; all his welds were defect free. They also were huge. Ginormous. Fat. Since nearly 100 had previously been made by a different supplier, we know it was possible - eventually the original welder was willing to go and show their guy how to put down a suitable bead, fast, defect free. The fat welds? 2-3 days per unit. The desired welds - 2-3 units get welded in a day.
Tackling deformation due to welding is a tough thing - it depends on how the part is restrained, how much the surrounding metal is heated, how much the melt zone shrinks with the dropping temperature which depends on how big the melt zone is. It very much depends on if the welding is symmetric or not, it depends on how fast the welder goes (affecting the size of the melt zone and the surround material expansion). Sometimes it depends on the crystalline state of the various components, going from face-centered cubic to body-centered cubic in the case of carbon steel.
Set up trial pieces and see how much deformation occurs with different approaches and how uniform the results are from some single approach.
