In Saxi: pick the same paper size, landscape, and untick “fit page”. Otherwise Saxi stretches the drawing to its own margins and the borders get lost.
Each pen is its own layer. Plot one layer, swap pens, then plot the other.
Drop SVGs anywhere on the page. Files starting with a column number (03-…) or containing someone's name find their own row, or drop one straight onto a row. Drag rows, or columns in the preview, to reorder them. Anyone without a drawing is left out and the rest spread evenly.